title
string | abstract
string | url
string | arxiv_id
string | date
string | category
string |
|---|---|---|---|---|---|
1.5-Femtosecond Delay in Charge Transfer
|
The transfer of population between two intersecting quantum states is the most fundamental dynamical event that governs a broad variety of processes in physics, chemistry, biology and material science. Whereas any two-state description implies that population leaving one state instantaneously appears in the other state, we show that coupling to additional states, present in all real-world systems, can cause a measurable delay in population transfer. Using attosecond spectroscopy supported by advanced quantum-chemical calculations, we measure a delay of 1.46$\pm$0.41 fs at a charge-transfer state crossing in CF$_3$I$^+$, where an electron hole moves from the fluorine atoms to iodine. Our measurements also fully resolve the other fundamental quantum-dynamical processes involved in the charge-transfer reaction: a vibrational rearrangement time of 9.38$\pm$0.21 fs (during which the vibrational wave packet travels to the state crossing) and a population-transfer time of 2.3-2.4 fs. Our experimental results and theoretical simulations show that delays in population transfer readily appear in otherwise-adiabatic reactions and are typically on the order of 1 fs for intersecting molecular valence states. These results have implications for many research areas, such as atomic and molecular physics, charge transfer or light harvesting.
|
https://arxiv.org/abs/2408.17402v1
|
2408.17402
|
2024-08-30
|
cybersecurity
|
15-GHz radio emission from nearby low-luminosity active galactic nuclei
|
We present a sub-arcsec resolution radio imaging survey of a sample of 76
low-luminosity active galactic nuclei (LLAGN) that were previously not detected
with the Very Large Array at 15 GHz. Compact, parsec-scale radio emission has
been detected above a flux density of 40 $\mu$Jy in 60% (45 of 76) of the LLAGN
sample. We detect 20 out of 31 (64%) low-ionization nuclear emission-line
region (LINER) nuclei, ten out of 14 (71%) low-luminosity Seyfert galaxies, and
15 out of 31 (48%) transition objects. We use this sample to explore
correlations between different emission lines and the radio luminosity. We also
populate the X-ray and the optical fundamental plane of black hole activity and
further refine its parameters. We obtain a fundamental plane relation of log
L$_\textrm{R}$ = $0.48\,(\pm0.04$) log L$_\textrm{X}$ + $0.79\,(\pm0.03$) log
$\textrm{M}$ and an optical fundamental plane relation of log L$_\textrm{R}$ =
$0.63\,(\pm 0.05)$ log L$_{[\rm O~III]}$ + $0.67\,(\pm 0.03)$ log $\textrm{M}$
after including all the LLAGN detected at high resolution at 15 GHz, and the
best-studied hard-state X-ray binaries (luminosities are given in erg s$^{-1}$
while the masses are in units of solar mass). Finally, we find conclusive
evidence that the nuclear 15 GHz radio luminosity function (RLF) of all the
detected Palomar Sample LLAGN has a turnover at the low-luminosity end, and is
best-fitted with a broken power law. The break in the power law occurs at a
critical mass accretion rate of 1.2$\times$10$^{-3}$ M$_{\odot}$/yr, which
translates to an Eddington ratio of $\rm \dot m_{Edd} \sim 5.1 \times 10^{-5}$,
assuming a black hole mass of 10$^9 M_{\odot}$. The local group stands closer
to the extrapolation of the higher-luminosity sources, and the classical
Seyferts agree with the nuclear RLF of the LLAGN in the local universe.
|
http://arxiv.org/abs/1805.06696v2
|
1805.06696
|
2018-05-18
|
cybersecurity
|
15 Keypoints Is All You Need
|
Pose tracking is an important problem that requires identifying unique human pose-instances and matching them temporally across different frames of a video. However, existing pose tracking methods are unable to accurately model temporal relationships and require significant computation, often computing the tracks offline. We present an efficient Multi-person Pose Tracking method, KeyTrack, that only relies on keypoint information without using any RGB or optical flow information to track human keypoints in real-time. Keypoints are tracked using our Pose Entailment method, in which, first, a pair of pose estimates is sampled from different frames in a video and tokenized. Then, a Transformer-based network makes a binary classification as to whether one pose temporally follows another. Furthermore, we improve our top-down pose estimation method with a novel, parameter-free, keypoint refinement technique that improves the keypoint estimates used during the Pose Entailment step. We achieve state-of-the-art results on the PoseTrack'17 and the PoseTrack'18 benchmarks while using only a fraction of the computation required by most other methods for computing the tracking information.
|
https://arxiv.org/abs/1912.02323v2
|
1912.02323
|
2019-12-05
|
cybersecurity
|
1.5 million materials narratives generated by chatbots
|
The advent of artificial intelligence (AI) has enabled a comprehensive exploration of materials for various applications. However, AI models often prioritize frequently encountered materials in the scientific literature, limiting the selection of suitable candidates based on inherent physical and chemical properties. To address this imbalance, we have generated a dataset of 1,494,017 natural language-material paragraphs based on combined OQMD, Materials Project, JARVIS, COD and AFLOW2 databases, which are dominated by ab initio calculations and tend to be much more evenly distributed on the periodic table. The generated text narratives were then polled and scored by both human experts and ChatGPT-4, based on three rubrics: technical accuracy, language and structure, and relevance and depth of content, showing similar scores but with human-scored depth of content being the most lagging. The merger of multi-modality data sources and large language model (LLM) holds immense potential for AI frameworks to help the exploration and discovery of solid-state materials for specific applications.
|
https://arxiv.org/abs/2308.13687v1
|
2308.13687
|
2023-08-25
|
cybersecurity
|
15M Multimodal Facial Image-Text Dataset
|
Currently, image-text-driven multi-modal deep learning models have demonstrated their outstanding potential in many fields. In practice, tasks centered around facial images have broad application prospects. This paper presents \textbf{FaceCaption-15M}, a large-scale, diverse, and high-quality dataset of facial images accompanied by their natural language descriptions (facial image-to-text). This dataset aims to facilitate a study on face-centered tasks. FaceCaption-15M comprises over 15 million pairs of facial images and their corresponding natural language descriptions of facial features, making it the largest facial image-caption dataset to date. We conducted a comprehensive analysis of image quality, text naturalness, text complexity, and text-image relevance to demonstrate the superiority of FaceCaption-15M. To validate the effectiveness of FaceCaption-15M, we first trained a facial language-image pre-training model (FLIP, similar to CLIP) to align facial image with its corresponding captions in feature space. Subsequently, using both image and text encoders and fine-tuning only the linear layer, our FLIP-based models achieved state-of-the-art results on two challenging face-centered tasks. The purpose is to promote research in the field of face-related tasks through the availability of the proposed FaceCaption-15M dataset. All data, codes, and models are publicly available. https://huggingface.co/datasets/OpenFace-CQUPT/FaceCaption-15M
|
https://arxiv.org/abs/2407.08515v2
|
2407.08515
|
2024-07-11
|
cybersecurity
|
1.5 {\mu}m Epitaxially Regrown Photonic Crystal Surface Emitting Laser Diode
|
We present an InP-based epitaxially regrown photonic crystal surface emitting
laser diode, lasing in quasi- CW conditions at 1523nm.
|
http://arxiv.org/abs/2010.09306v1
|
2010.09306
|
2020-10-19
|
cybersecurity
|
15N Fractionation in Infrared-Dark Cloud Cores
|
Nitrogen is one of the most abundant elements in the Universe and its 14N/15N
isotopic ratio has the potential to provide information about the initial
environment in which our Sun formed. Recent findings suggest that the Solar
System may have formed in a massive cluster since the presence of short-lived
radioisotopes in meteorites can only be explained by the influence of a
supernova. The aim of this project is to determine the 14N/15N ratio towards a
sample of cold, massive dense cores at the initial stages in their evolution.
We have observed the J=1-0 transitions of HCN, H13CN, HC15N, HN13C and H15NC
toward a sample of 22 cores in 4 Infrared-Dark Clouds (IRDCs). IRDCs are
believed to be the precursors of high-mass stars and star clusters. Assuming
LTE and a temperature of 15K, the column densities of HCN, H13CN, HC15N, HN13C
and H15NC are calculated and their 14N/15N ratio is determined for each core.
The 14N/15N ratio measured in our sample of IRDC cores range between ~70 and
>763 in HCN and between ~161 and ~541 in HNC. They are consistent with the
terrestrial atmosphere (TA) and protosolar nebula (PSN) values, and with the
ratios measured in low-mass pre-stellar cores. However, the 14N/15N ratios
measured in cores C1, C3, F1, F2 and G2 do not agree with the results from
similar studies toward the same massive cores using nitrogen bearing molecules
with nitrile functional group (-CN) and nitrogen hydrides (-NH) although the
ratio spread covers a similar range. Amongst the 4 IRDCs we measured relatively
low 14N/15N ratios towards IRDC G which are comparable to those measured in
small cosmomaterials and protoplanetary disks. The low average gas density of
this cloud suggests that the gas density, rather than the gas temperature, may
be the dominant parameter influencing the initial nitrogen isotopic composition
in young PSN.
|
http://arxiv.org/abs/1705.04082v1
|
1705.04082
|
2017-05-11
|
cybersecurity
|
15NH3 in the atmosphere of a cool brown dwarf
|
Brown dwarfs serve as ideal laboratories for studying the atmospheres of giant exoplanets on wide orbits as the governing physical and chemical processes in them are nearly identical. Understanding the formation of gas giant planets is challenging, often involving the endeavour to link atmospheric abundance ratios, such as the carbon-to-oxygen (C/O) ratio, to formation scenarios. However, the complexity of planet formation requires additional tracers, as the unambiguous interpretation of the measured C/O ratio is fraught with complexity. Isotope ratios, such as deuterium-to-hydrogen and 14N/15N, offer a promising avenue to gain further insight into this formation process, mirroring their utility within the solar system. For exoplanets only a handful of constraints on 12C/13C exist, pointing to the accretion of 13C-rich ice from beyond the disks' CO iceline. Here we report on the mid-infrared detection of the 14NH3 and 15NH3 isotopologues in the atmosphere of a cool brown dwarf with an effective temperature of 380 K in a spectrum taken with the Mid-InfraRed Instrument of the James Webb Space Telescope. As expected, our results reveal a 14N/15N value consistent with star-like formation by gravitational collapse, demonstrating that this ratio can be accurately constrained. Since young stars and their planets should be more strongly enriched in the 15N isotope, we expect that 15NH3 will be detectable in a number of cold, wide-separation exoplanets.
|
https://arxiv.org/abs/2311.08054v1
|
2311.08054
|
2023-11-14
|
cybersecurity
|
15-nodal quartic surfaces.I: quintic del Pezzo surfaces and congruences of lines in $\bbP^3$
|
We explain a classical construction of a del Pezzo surface of degree d = 4 or
5 as a smooth order two congruence of lines in 3-space whose focal surface is a
quartic surface $X_{20-d}$ with 20-d ordinary double points. We also show that
$X_{15}$ can be realized as a hyperplane section of the
Castelnuovo-Richmond-Igusa quartic hypersurface. This leads to the proof of
rationality of the moduli space of 15-nodal quartic surfaces. We discuss some
other birational models of $X_{15}$: quartic symmetroids, 5-nodal quartic
surfaces, 10-nodal sextic surfaces in $P^4$ and nonsingular surfaces of degree
10 in $P^6$. Finally we study some birational involutions of a 15-nodal quartic
surface which, as it is shown in Part 2 of the paper jointly with I. Shimada,
belong to a finite set of generators of the group of birational automorphisms
of a general 15-nodal quartic surface.
|
http://arxiv.org/abs/1906.12295v2
|
1906.12295
|
2019-09-23
|
cybersecurity
|
15-nodal quartic surfaces. Part II: The automorphism group
|
We describe a set of generators and defining relations for the group of
birational automorphisms of a general 15-nodal quartic surface in the complex
projective 3-dimensional space.
|
http://arxiv.org/abs/1908.05390v3
|
1908.05390
|
2019-10-28
|
cybersecurity
|
1.5-Pints Technical Report: Pretraining in Days, Not Months -- Your Language Model Thrives on Quality Data
|
This paper presents a compute-efficient approach to pre-training a Language Model-the "1.5-Pints"-in only 9 days, while outperforming state-of-the-art models as an instruction-following assistant.Based on MT-Bench (a benchmark that emulates human judgments), 1.5-Pints outperforms Apple's OpenELM and Microsoft's Phi.This is achieved by a carefully curated pre-training dataset of 57 billion tokens, using a mix of automated workflows and manual human review. The selection of the dataset prioritizes content that is considered expository and "textbook-like" to aid the model in reasoning and logical deduction, culminating in its overall ability as a strong and versatile AI model. In terms of the model architecture, we employed a modified Mistral tokenizer, alongside a Llama-2 architecture for wider compatibility. For training, we adopted the methodologies used by StableLM, TinyLlama, and Huggingface Zephyr. 1.5-Pints demonstrates that by focusing on data quality over quantity in LLM training, we can significantly reduce training time and resources required. We believe this approach will not only make pre-training more accessible but also reduce our carbon footprint. Our findings and resources from this research are open-sourced, aiming to facilitate further advancements in the field. The 1.5-Pints model is available in two versions: 2K and 16K context windows.
|
https://arxiv.org/abs/2408.03506v1
|
2408.03506
|
2024-08-07
|
cybersecurity
|
15 Years of Algorithmic Fairness -- Scoping Review of Interdisciplinary Developments in the Field
|
This paper presents a scoping review of algorithmic fairness research over the past fifteen years, utilising a dataset sourced from Web of Science, HEIN Online, FAccT and AIES proceedings. All articles come from the computer science and legal field and focus on AI algorithms with potential discriminatory effects on population groups. Each article is annotated based on their discussed technology, demographic focus, application domain and geographical context. Our analysis reveals a growing trend towards specificity in addressed domains, approaches, and demographics, though a substantial portion of contributions remains generic. Specialised discussions often concentrate on gender- or race-based discrimination in classification tasks. Regarding the geographical context of research, the focus is overwhelming on North America and Europe (Global North Countries), with limited representation from other regions. This raises concerns about overlooking other types of AI applications, their adverse effects on different types of population groups, and the cultural considerations necessary for addressing these problems. With the help of some highlighted works, we advocate why a wider range of topics must be discussed and why domain-, technological, diverse geographical and demographic-specific approaches are needed. This paper also explores the interdisciplinary nature of algorithmic fairness research in law and computer science to gain insight into how researchers from these fields approach the topic independently or in collaboration. By examining this, we can better understand the unique contributions that both disciplines can bring.
|
https://arxiv.org/abs/2408.01448v1
|
2408.01448
|
2024-07-23
|
cybersecurity
|
15 years of VLT/UVES OH intensities and temperatures in comparison with TIMED/SABER data
|
The high-resolution echelle spectrograph UVES of the Very Large Telescope at
Cerro Paranal in Chile has been regularly operated since April 2000. Thus, UVES
archival data originally taken for astronomical projects but also including sky
emission can be used to study airglow variations on a time scale longer than a
solar cycle. Focusing on OH emission and observations until March 2015, we
considered about 3,000 high-quality spectra from two instrumental set-ups
centred on 760 and 860 nm, which cover about 380 nm each. These data allowed us
to measure line intensities for several OH bands in order to derive band
intensities and rotational temperatures for different upper vibrational levels
as a function of solar activity and observing date. The results were compared
with those derived from emission and temperature profile data of the radiometer
SABER on the TIMED satellite taken in the Cerro Paranal area between 2002 and
2015. In agreement with the SABER data, the long-term variations in OH
intensity and temperature derived from the UVES data are dominated by the solar
cycle, whereas secular trends appear to be negligible. Combining the UVES and
SABER results, the solar cycle effects for the OH intensity and temperature are
about 12 to 17% and 4 to 5 K per 100 sfu and do not significantly depend on the
selected OH band. The data also reveal that variations of the effective OH
emission layer height and air density can cause significant changes in the OH
rotational temperatures due to a varying ratio of OH thermalising collisions by
air molecules and OH radiation, deactivation, and destruction processes which
impede the rotational relaxation. However, this effect appears to be of minor
importance for the explanation of the rotational temperature variations related
to the solar activity cycle, which causes only small changes in the OH emission
profile.
|
http://arxiv.org/abs/1705.07239v1
|
1705.07239
|
2017-05-20
|
cybersecurity
|
16,051 formulas for Ottaviani's invariant of cubic threefolds
|
We provide explicit combinatorial formulas for Ottaviani's degree 15
invariant which detects cubics in 5 variables that are sums of 7 cubes. Our
approach is based on the chromatic properties of certain graphs and relies on
computer searches and calculations.
|
http://arxiv.org/abs/1402.2669v2
|
1402.2669
|
2015-04-30
|
cybersecurity
|
1.60 m Telescope P-E
|
A comparative the telescope twin P-E, one is in Observat\'orio Pico dos Dias,
Brazil, other in Observatoire Mont-M\'egantic, Qu\'ebec, Canada. The same
project, the same beginning configuration but different stories, different
solutions for the problems by the years.
|
http://arxiv.org/abs/1501.07333v1
|
1501.07333
|
2015-01-29
|
cybersecurity
|
160 ps Yb:YAG/Cr:YAG microchip laser
|
By cryogenically cooling the Yb:YAG/Cr:YAG medium, one can break through the
damage limit of Yb:YAG/Cr:YAG passively Q-switched microchip lasers at room
temperature and thus achieve a shorter minimum pulse duration. In the proof of
principle experiment we carried out, a 160.6 ps pulse duration was obtained. To
the best of our knowledge, this is the first realization of sub-200 ps pulse
operation for an Yb:YAG/Cr:YAG microchip laser
|
http://arxiv.org/abs/1805.09471v1
|
1805.09471
|
2018-05-24
|
cybersecurity
|
$ {}^{164} \mathrm{Pb} $: A possible heaviest $ N = Z $ doubly magic nucleus
|
We confirm by using the Skyrme Hartree-Fock-Bogoliubov calculation that $ {}^{164} \mathrm{Pb} $ is a possible heaviest $ N = Z $ doubly magic nucleus whose lifetime is long enough to be measured on accelerator experiments. We estimate the proton-emission and alpha-decay half-lives of $ {}^{164} \mathrm{Pb} $. The estimated proton-emission half-life ranges from $ 0.1 \, \mathrm{ps} $ to $ 10 \, \mathrm{ns} $, while the alpha decay can be safely neglected.
|
https://arxiv.org/abs/2405.12095v2
|
2405.12095
|
2024-05-20
|
cybersecurity
|
16-channel Photonic Solver for Optimization Problems on a Silicon Chip
|
In this article, we proposed a programmable 16-channel photonic solver for quadratic unconstrained binary optimization (QUBO) problems. The solver is based on a hybrid optoelectronic scheme including a photonic chip and the corresponding electronic driving circuit. The photonic chip is fabricated on silicon on insulator (SOI) substrate and integrates high-speed electro-optic modulators, thermo-optic phase shifters and photodetectors to conduct the 16-dimensional optical vector-matrix multiplication (OVMM). Due to the parallel and low latency propagation of lightwave, the calculation of the QUBO cost function can be accelerated. Besides, the electronic processor is employed to run the heuristic algorithm to search the optimal solution. In the experiment, two 16-dimensional randomly generated QUBO problems are solved with high successful probabilities. To our knowledge, it is the largest scale of programmable and on-chip photonic solver ever reported. Moreover, the computing speed of the OVMM on photonic chip is ~2 TFLOP/s. It shows the potential of fast solving such optimization problems with integrated photonic systems.
|
https://arxiv.org/abs/2407.04713v1
|
2407.04713
|
2024-06-05
|
cybersecurity
|
16D anisotropic inharmonic oscillator and 9D related (MICZ-)Kepler-like systems
|
We present some generalization of 16D oscillator by anisotropic and nonlinear
inharmonic terms and its dual analog for 9D related MICZ-Kepler systems by
generalized version of the Kustaanheimo-Stiefel transformation. The solvability
of the Schr\"{o}dinger equation of the these problems by the variables
separation method are discussed in different coordinates.
|
http://arxiv.org/abs/1903.10847v1
|
1903.10847
|
2019-03-24
|
cybersecurity
|
16-Element Superconducting Nanowire Single-Photon Detector for Gigahertz Counting at 1550-nm
|
We present a linearly arrayed, 16-element, superconducting nanowire single-photon detector with 83.4$\%$ system detection efficiency at 1550 nm and a mean per-element dead-time of 9.6-ns, enabling counting at 1 giga-count per second with $>50\%$ System Detection Efficiency. This device was designed and fabricated in an existing scalable commercial process.
|
https://arxiv.org/abs/2103.14086v1
|
2103.14086
|
2021-03-25
|
cybersecurity
|
1.6 GHz Frequency Scanning of a 482 nm Laser Stabilized using Electromagnetically Induced Transparency
|
We propose a method to continuously frequency shift a target laser that is frequency stabilized by a reference laser, which is several hundreds of nanometers detuned. We demonstrate the technique using the 5S 1/2 to 5P 3/2 to 29D 5/2 Rydberg transition in 87Rb vapor and lock the 482 nm target laser to the 780 nm reference laser using the cascaded electromagnetically induced transparency signal. The stabilized frequency of the target laser can be shifted by about 1.6 GHz by phase modulating the reference laser using a waveguide-type electro-optical modulator. This simple method for stable frequency shifting can be used in atomic or molecular physics experiments that require a laser frequency scanning range on the order of several GHz.
|
https://arxiv.org/abs/2104.11423v1
|
2104.11423
|
2021-04-23
|
cybersecurity
|
$^{16}\mathrm{O}^{16}\mathrm{O}$ at RHIC and the LHC comparing $α$ clustering vs substructure
|
Collisions of light and heavy nuclei in relativistic heavy-ion collisions have been shown to be sensitive to nuclear structure. With a proposed $^{16}\mathrm{O}^{16}\mathrm{O}$ run at the LHC and RHIC we study the potential for finding $\alpha$ clustering in $^{16}$O. Here we use the state-of-the-art iEBE-VISHNU package with $^{16}$O nucleonic configurations from {\rm ab initio} nuclear lattice simulations. This setup was tuned using a Bayesian analysis on pPb and PbPb systems. We find that the $^{16}\mathrm{O}^{16}\mathrm{O}$ system always begins far from equilibrium and that at LHC and RHIC it approaches the regime of hydrodynamic applicability only at very late times. Finally, by taking ratios of flow harmonics we are able to find measurable differences between $\alpha$-clustering, nucleonic, and subnucleonic degrees of freedom in the initial state.
|
https://arxiv.org/abs/2103.03345v1
|
2103.03345
|
2021-03-04
|
cybersecurity
|
16O electroweak response functions from first principles
|
We present calculations of various electroweak response functions for the 16O nucleus obtained using coupled-cluster theory in conjunction with the Lorentz integral transform method. We employ nuclear forces derived at next-to-leading order and next-to-next-to-leading order in chiral effective field theory and perform a Bayesian analysis to assess uncertainties. Our results are in good agreement with available electron-scattering data at q~ 326 MeV/c. Additionally, we provide several predictions for the weak response functions in the quasi-elastic peak region at q= 300 and 400 MeV/c, which are critical for long-baseline neutrino experiments.
|
https://arxiv.org/abs/2410.05962v1
|
2410.05962
|
2024-10-08
|
cybersecurity
|
$^{16}O(p,\alpha)^{13}N$ makes explosive oxygen burning sensitive to the metallicity of the progenitors of type Ia supernovae
|
Even though the main nucleosynthetic products of type Ia supernovae belong to
the iron-group, intermediate-mass alpha-nuclei (silicon, sulfur, argon, and
calcium) stand out in their spectra up to several weeks past maximum
brightness. Recent measurements of the abundances of calcium, argon, and sulfur
in type Ia supernova remnants have been interpreted in terms of
metallicity-dependent oxygen burning, in accordance with previous theoretical
predictions. It is known that $\alpha$-rich oxygen burning results from
$^{16}$O$\rightarrow^{12}$C followed by efficient $^{12}$C+$^{12}$C fusion
reaction, as compared to oxygen consumption by $^{16}$O fusion reactions, but
the precise mechanism of dependence on the progenitor metallicity has remained
unidentified so far. I show that the chain
$^{16}$O(p,$\alpha$)$^{13}$N($\gamma$,p)$^{12}$C boosts $\alpha$-rich oxygen
burning when the proton abundance is large, increasing the synthesis of argon
and calcium with respect to sulfur and silicon. For high-metallicity
progenitors, the presence of free neutrons leads to a drop in the proton
abundance and the above chain is not efficient. Although the rate of
$^{16}$O(p,$\alpha$)$^{13}$N can be found in astrophysical reaction rate
libraries, its uncertainty is unconstrained. Assuming that all reaction rates
other than $^{16}$O(p,$\alpha$)$^{13}$N retain their standard values, an
increase by a factor of approximately seven of the $^{16}$O(p,$\alpha$)$^{13}$N
rate at temperatures in the order $3-5\times10^9$ K is enough to explain the
whole range of calcium-to-sulfur mass ratios measured in Milky Way and LMC
supernova remnants. These same measurements provide a lower limit to the
$^{16}$O(p,$\alpha$)$^{13}$N rate in the mentioned temperature range, on the
order of a factor of 0.5 with respect to the rate reported in widely used
literature tabulations.
|
http://arxiv.org/abs/1907.01158v2
|
1907.01158
|
2019-07-15
|
cybersecurity
|
$^{16}$O spectral function from coupled-cluster theory: applications to lepton-nucleus scattering
|
We calculate the $^{16}$O spectral function by combining coupled-cluster theory with a Gaussian integral transform and by expanding the integral kernel in terms of Chebyshev polynomials to allow for a quantification of the theoretical uncertainties. We perform an analysis of the spectral function and employ it to predict lepton-nucleus scattering. Our results well describe the $^{16}$O electron scattering data in the quasi-elastic peak for momentum transfers $|\mathbf{q}|\gtrapprox500$ MeV and electron energies up to 1.2 GeV, extending therefore the so-called first principles approach to lepton-nucleus cross sections well into the relativistic regime. To prove the applicability of this method to neutrino-nucleus cross sections, we implement our $^{16}$O spectral functions in the NuWro Monte Carlo event generator and provide a comparison with recently published T2K neutrino data.
|
https://arxiv.org/abs/2309.00355v1
|
2309.00355
|
2023-09-01
|
cybersecurity
|
16O within the Semimicroscopic Algebraic Cluster Model and the importance of the Pauli Exclusion Principle
|
The Semimicroscopic Algebraic Cluster Model (SACM) is applied to 16O, assumed
to consist of a system of four alpha-clusters. For the 4-alpha cluster system a
microscopic model space is constructed, which observes the
Pauli-Exclusion-Principle (PEP) and is symmetric under permutation of the
4-alpha-particles. A phenomenological Hamiltonian is used, justifying the name
Semi in the SACM. The spectrum and transition values are determined. One of the
main objectives is to test the importance of the Pauli Exclusion Principle
(PEP), comparing the results with the Algebraic Cluster Model (ACM), which does
not include the PEP, and claims that the 16O shows evidence of a tetrahedral
structure, which can be explained easily by symmetry arguments. We show that
PEP is very important and cannot be neglected, otherwise it leads to a wrong
interpretation of the band structure and to too many states at low energy.
|
http://arxiv.org/abs/1901.04883v2
|
1901.04883
|
2019-01-17
|
cybersecurity
|
16 Propositions to Reconsider the Organization of a Scientific Workshop
|
Participating a scientific workshop is nowadays often an adventure because the number of participants do seldom exceed the number of talks. A half-day workshop is mostly finished at lunchtime, speakers are sometimes not present and unexcused, and a strict progression of the workshop offers little air for discussion. And when talks are re-scheduled on short notice in case that a speech is dropped out, attaining guests definitely wonder why the presenter is talking about something that does not match the previously announced talk. In this respect, we believe that the organization of a workshop in the classical sense must be reconsidered. It is not enough of compelling the presenters to pay the registration fee only and to let the participants being impassive or taken away mentally. With this work, we address several propositions to become implemented in the future workshop organization. With that, we hope to contribute to the identification of scientific workshops as a place of interaction.
|
https://arxiv.org/abs/0809.4916v1
|
0809.4916
|
2008-09-29
|
cybersecurity
|
16 QAM Communication with 1-Bit Transmitters
|
We present a novel non-linear precoding technique for the transmission of 16
quadrature amplitude modulation (QAM) symbols in a 1-bit massive multi-user
(MU) multipleinput- single-output (MISO) downlink system. We deploy low
resolution digital-to-analog converters (DACs) at the transmitter for the sake
of decreasing the high energy consumption related to the massive MISO system.
To mitigate the multi-user interference (MUI) and the distortions due to the
low resolution DACs, the minimum bit error ratio (MBER) precoder was introduced
in previous work. However, this precoder technique is restricted to quadrature
phase shift keying (QPSK) signaling. Our approach consists in upgrading this
method to the transmission of 16 QAM symbols. Simulation results show that the
performance in terms of uncoded BER is significantly improved for larger
massive MISO gain.
|
http://arxiv.org/abs/1612.05286v1
|
1612.05286
|
2016-12-15
|
cybersecurity
|
16-qubit IBM universal quantum computer can be fully entangled
|
Entanglement is an important evidence that a quantum device can potentially solve problems intractable for classical computers. In this paper, we prepare connected graph states involving 8 to 16 qubits on ibmqx5, a 16-qubit superconducting quantum processor accessible via IBM cloud,using low-depth circuits. We demonstrate that the prepared state is fully entangled, i.e. the state is inseparable with respect to any fixed partition.
|
https://arxiv.org/abs/1801.03782v3
|
1801.03782
|
2018-01-11
|
cybersecurity
|
1.6 Tbps Classical Channel Coexistence With DV-QKD Over Hollow Core Nested Antiresonant Nodeless Fibre (HC-NANF)
|
We demonstrate for the first time the coexistence of a quantum-channel and 8x200 Gpbs 16-QAM optical channels with launching powers as high as -9dBm per channel in a 2 km HC-NANF. Comparative analysis with single-mode fibre reveals that the quantum channel could not be sustained at such power levels.
|
https://arxiv.org/abs/2106.14560v2
|
2106.14560
|
2021-06-28
|
cybersecurity
|
16th Joint ACL - ISO Workshop on Interoperable Semantic Annotation PROCEEDINGS
|
https://aclanthology.org/2020.isa-1.0
| null |
2020-05-01
|
cybersecurity
|
|
16 Ways to Gallop: Energetics and Body Dynamics of High-Speed Quadrupedal Gaits
|
Galloping is a common high-speed gait in both animals and quadrupedal robots, yet its energetic characteristics remain insufficiently explored. This study systematically analyzes a large number of possible galloping gaits by categorizing them based on the number of flight phases per stride and the phase relationships between the front and rear legs, following Hildebrand's framework for asymmetrical gaits. Using the A1 quadrupedal robot from Unitree, we model galloping dynamics as a hybrid dynamical system and employ trajectory optimization (TO) to minimize the cost of transport (CoT) across a range of speeds. Our results reveal that rotary and transverse gallop footfall sequences exhibit no fundamental energetic difference, despite variations in body yaw and roll motion. However, the number of flight phases significantly impacts energy efficiency: galloping with no flight phases is optimal at lower speeds, whereas galloping with two flight phases minimizes energy consumption at higher speeds. We validate these findings using a quadratic programming (QP)-based controller, developed in our previous work, in Gazebo simulations. These insights advance the understanding of quadrupedal locomotion energetics and may inform future legged robot designs for adaptive, energy-efficient gait transitions.
|
https://arxiv.org/abs/2503.13716v1
|
2503.13716
|
2025-03-17
|
cybersecurity
|
16 Years of SPEC Power: An Analysis of x86 Energy Efficiency Trends
|
The SPEC Power benchmark offers valuable insights into the energy efficiency of server systems, allowing comparisons across various hardware and software configurations. Benchmark results are publicly available for hundreds of systems from different vendors, published since 2007. We leverage this data to perform an analysis of trends in x86 server systems, focusing on power consumption, energy efficiency, energy proportionality and idle power consumption. Through this analysis, we aim to provide a clearer understanding of how server energy efficiency has evolved and the factors influencing these changes.
|
https://arxiv.org/abs/2411.07062v1
|
2411.07062
|
2024-11-11
|
cybersecurity
|
16 years of Ulysses Interstellar Dust Measurements in the Solar System: II. Fluctuations in the Dust Flow from the Data
|
The Ulysses spacecraft provided the first opportunity to identify and study
Interstellar Dust (ISD) in-situ in the Solar System between 1992 and 2007. Here
we present the first comprehensive analysis of the ISD component in the entire
Ulysses dust data set. We analysed several parameters of the ISD flow in a
time-resolved fashion: flux, flow direction, mass index, and flow width. The
general picture is in agreement with a time-dependent focussing/defocussing of
the charged dust particles due to long-term variations of the solar magnetic
field throughout a solar magnetic cycle of 22 years. In addition, we confirm a
shift in dust direction of $50^{\circ} \pm 7^{\circ}$ in 2005, along with a
steep, size-dependent increase in flux by a factor of 4 within 8 months. To
date, this is difficult to interpret and has to be examined in more detail by
new dynamical simulations. This work is part of a series of three papers. This
paper concentrates on the time-dependent flux and direction of the ISD. In a
companion paper (Kr\"uger et al., 2015) we analyse the overall mass
distribution of the ISD measured by Ulysses, and a third paper discusses the
results of modelling the flow of the ISD as seen by Ulysses (Sterken et al.,
2015).
|
http://arxiv.org/abs/1508.03242v1
|
1508.03242
|
2015-08-13
|
cybersecurity
|
16 Years of Ulysses Interstellar Dust Measurements in the Solar System: I. Mass Distribution and Gas-to-Dust Mass Ratio
|
In the early 1990s, contemporary interstellar dust (ISD) penetrating deep
into the heliosphere was identified with the in-situ dust detector on board the
Ulysses spacecraft. Between 1992 and the end of 2007 Ulysses monitored the ISD
stream. The interstellar grains act as tracers of the physical conditions in
the local interstellar medium surrounding our solar system. Earlier analyses of
the Ulysses ISD data measured between 1992 and 1998 implied the existence of
'big' ISD grains [up to 10^-13kg]. The derived gas-to-dust-mass ratio was
smaller than the one derived from astronomical observations, implying a
concentration of ISD in the very local interstellar medium. We analyse the
entire data set from 16 yr of Ulysses ISD measurements in interplanetary space.
This paper concentrates on the overall mass distribution of ISD. An
accompanying paper investigates time-variable phenomena in the Ulysses ISD
data, and in a third paper we present the results from dynamical modelling of
the ISD flow applied to Ulysses. We use the latest values for the interstellar
hydrogen and helium densities, the interstellar helium flow speed of
v_ISM,inf=23.2km/s, and the ratio of radiation pressure to gravity, beta,
calculated for astronomical silicates. We find a gas-to-dust-mass ratio in the
local interstellar cloud of R_g/d=193^+85_-57, and a dust density of
2.1+/-0.6x10^-24kg/m^3. For a higher inflow speed of 26km/s, the
gas-to-dust-mass ratio is 20% higher, and, accordingly, the dust density is
lower by the same amount. The gas-to-dust mass ratio derived from our new
analysis is compatible with the value most recently determined from
astronomical observations. We confirm earlier results that the very local
interstellar medium contains 'big' (i.e. 1 um-sized) ISD grains. We find a dust
density in the local interstellar medium that is a factor of three lower than
values implied by earlier analyses.
|
http://arxiv.org/abs/1510.06180v1
|
1510.06180
|
2015-10-21
|
cybersecurity
|
17,000 %/W Second Harmonic Conversion Efficiency in Single Crystalline Aluminum Nitride Microresonators
|
High quality factor optical microcavities have been employed in a variety of
material systems to enhance nonlinear optical interactions. While
single-crystalline aluminum nitride microresonators have recently emerged as a
low loss platform for integrated nonlinear optics such as four wave mixing and
Raman lasing, few studies have investigated this material for second-harmonic
generation. In this Letter, we demonstrate an optimized fabrication of
dually-resonant phase-matched ring resonators from epitaxial aluminum nitride
thin films. An unprecendented second-harmonic generation efficiency of
17,000%/W is obtained in the low power regime and pump depletion is observed at
a relatively low input power of 3.5 mW. This poses epitaxial aluminum nitride
as the highest efficiency second-harmonic generator among current integrated
platforms.
|
http://arxiv.org/abs/1807.09638v3
|
1807.09638
|
2018-09-25
|
cybersecurity
|
1700 Forests
|
Since ordered trees and Dyck paths are equinumerous, so are ordered forests
and grand-Dyck paths that start with an upwards step.
|
http://arxiv.org/abs/1608.08740v1
|
1608.08740
|
2016-08-31
|
cybersecurity
|
170-260 GHz Sub-THz Optical Heterodyne Analog Radio-over-Fiber Link for 6G Wireless System
|
The frequency and phase fluctuations of free-running lasers limit the performance of optical heterodyne sub-THz systems - especially for low subcarrier spacing OFDM signals. Digital impairment compensation is implemented here for the successful generation of 170 - 260 GHz sub-THz OFDM signals over 10km analog-RoF link.
|
https://arxiv.org/abs/2309.16696v1
|
2309.16696
|
2023-08-10
|
cybersecurity
|
1.71 Tb/s Single-Channel and 56.51 Tb/s DWDM Transmission over 96.5 km Field-Deployed SSMF
|
We report an industry leading optical dense wavelength division multiplexing (DWDM) field trial with line rates per channel exceeding 1.66 Tb/s using 130 GBaud dual-polarization probabilistic constellation shaping 256-ary quadrature amplitude modulation (DP-PCS256QAM) in a high capacity data center interconnect (DCI) scenario. This research trial was performed on 96.5 km of field-deployed standard single mode G.652 fiber infrastructure of Deutsche Telekom in Germany employing Erbium-doped fiber amplifier (EDFA)-only amplification. A total of 34 channels were transmitted with 150 GHz spacing for a total fiber capacity of 56.51 Tb/s and a spectral efficiency higher than 11bit/s/Hz. In the single-channel transmission scenario 1.71 Tb/s was achieved over the same link. In addition, we successfully demonstrate record net bitrates of 1.88 Tb/s in back-to-back (B2B) using 130 GBaud DP-PCS400QAM.
|
https://arxiv.org/abs/2108.01873v1
|
2108.01873
|
2021-08-04
|
cybersecurity
|
$^{171}$Yb$^+$ optical clock with $2.2\times 10^{-18}$ systematic uncertainty and absolute frequency measurements
|
A full evaluation of the uncertainty budget for the ytterbium ion optical clock at the National Physical Laboratory (NPL) was performed on the electric octupole (E3) $^2\mathrm{S}_{1/2}\,\rightarrow\, ^2\mathrm{F}_{7/2}$ transition. The total systematic frequency shift was measured with a fractional standard systematic uncertainty of $2.2\times 10^{-18}$. Furthermore, the absolute frequency of the E3 transition of the $^{171}$Yb$^+$ ion was measured between 2019 and 2023 via a link to International Atomic Time (TAI) and against the local caesium fountain NPL-CsF2. The absolute frequencies were measured with fractional standard uncertainties between $3.7 \times 10^{-16}$ and $1.1 \times 10^{-15}$, and all were in agreement with the 2021 BIPM recommended frequency.
|
https://arxiv.org/abs/2403.14423v1
|
2403.14423
|
2024-03-21
|
cybersecurity
|
1720nm-1800nm tunable chirped pulse amplification based on thulium-doped fiber
|
Chirped pulse amplification (CPA) has been adopted as a commonly used methodology to obtain powerful ultrashort laser pulses since its first demonstration. However, wavelength-tunable CPA systems are rarely reported. Wavelength-tunable ultrashort and intense laser pulses are desired in various fields like nonlinear spectroscopy and optical parametric amplification. In this work, we report a 1720 nm -1800 nm tunable CPA system based on a single-mode Tm-doped fiber covering the middle wavelength band of the third biological window. The tunable CPA system delivers ultrashort pulses varied between ~300 to 500 fs depending on the central wavelength emission at the fixed repetition rate of 22.7 MHz. The maximum average power ranges from 126 mW at 1720 nm to 294 mW at 1800 nm following the gain shape of Tm-doped fiber. Considering the specific wave-length range, this tunable CPA system is highly desired for biomedical imaging, sensing and parametric amplifiers for mid-infrared light generation.
|
https://arxiv.org/abs/2312.06223v1
|
2312.06223
|
2023-12-11
|
cybersecurity
|
$^{174}\mathrm{Yb}^+$-$^{113}\mathrm{Cd}^+$ sympathetic-cooling bi-species Coulomb crystal applied to microwave frequency standard
|
We reported the realization of a $^{174}\mathrm{Yb}^+$-$^{113}\mathrm{Cd}^+$ bi-species Coulomb crystal comprising $^{174}\mathrm{Yb}^+$ ions as coolant and verified its potential for application as a $^{113}\mathrm{Cd}^+$ microwave frequency standard employing sympathetic cooling.The two species of massive ions stably trapped in a Paul trap make up this large two-component crystal. The $^{113}\mathrm{Cd}^+$ ions are trapped in the center, which reduces considerably RF heating and excess micromotion to which the $^{113}\mathrm{Cd}^+$ ions are subjected. Under this scheme, the uncertainty due to the second-order Doppler effect is reduced to $5\times10^{-16}$, which represents an order of magnitude improvement over sympathetic cooled $^{40}\mathrm{Ca}^+$-$^{113}\mathrm{Cd}^+$ crystal. The uncertainty from the second-order Zeeman effect, which contributes the largest uncertainty to the microwave-ion frequency standard, is reduced to $4\times10^{-16}$. The relevant AC Stark shift uncertainty is estimated to be $4\times10^{-19}$. These results indicate using $^{174}\mathrm{Yb}^+$ as coolant ions for $^{113}\mathrm{Cd}^+$ is far superior and confirm the feasibility of a sympathetic-cooled cadmium-ion microwave clock system employing a $^{174}\mathrm{Yb}^+$-$^{113}\mathrm{Cd}^+$ two-component crystal.
|
https://arxiv.org/abs/2307.01656v1
|
2307.01656
|
2023-07-04
|
cybersecurity
|
174P/Echeclus and its Blue Coma Observed Post-outburst
|
It has been suggested that centaurs may lose their red surfaces and become
bluer due to the onset of cometary activity, but the way in which cometary
outbursts affect the surface composition and albedo of active centaurs is
poorly understood. We obtained consistent visual-near-infrared (VNIR)
reflectance spectra of the sporadically active centaur 174P/Echeclus during a
period of inactivity in 2014 and six weeks after its outburst in 2016 to see if
activity had observably changed the surface properties of the nucleus. We
observed no change in the surface reflectance properties of Echeclus following
the outburst compared to before, indicating that, in this case, any surface
changes due to cometary activity were not sufficiently large to be observable
from Earth. Our spectra and post-outburst imaging have revealed, however, that
the remaining dust coma is not only blue compared to Echeclus, but also bluer
than solar, with a spectral gradient of -7.7+/-0.6% per 0.1 micron measured
through the 0.61-0.88 micron wavelength range that appears to continue up to a
wavelength of around 1.3 micron before becoming neutral. We conclude that the
blue visual color of the dust is likely not a scattering effect, and instead
may be indicative of the dust's carbon-rich composition. Deposition of such
blue, carbon-rich, comatic dust onto a red active centaur may be a mechanism by
which its surface color could be neutralized.
|
http://arxiv.org/abs/1811.11220v3
|
1811.11220
|
2019-01-24
|
cybersecurity
|
$^{176}$Lu$^+$ clock comparison at the $10^{-18}$ level via correlation spectroscopy
|
We experimentally demonstrate agreement between two $^{176}$Lu$^+$ frequency references using correlation spectroscopy. From a comparison at different magnetic fields, we obtain a quadratic Zeeman coefficient of $-4.89264(88)\,\mathrm{Hz/mT^2}$, which gives a corresponding fractional frequency uncertainty contribution of just $2.5\times 10^{-20}$ for comparisons at typical operating fields of 0.1\,mT. A subsequent comparison with both systems at 0.1\,mT, demonstrates a fractional frequency difference of $(-2.0\pm(3.7)_\mathrm{stat}\pm(0.9)_\mathrm{sys})\times10^{-18}$, where `stat' and `sys' indicate statistical and systematic uncertainty, respectively.
|
https://arxiv.org/abs/2212.04652v1
|
2212.04652
|
2022-12-09
|
cybersecurity
|
$^{177}$Lu SPECT Imaging in the Presence of $^{90}$Y: Does $^{90}$Y Degrade Image Quantification? A Simulation Study
|
This work aims to investigate the accuracy of quantitative SPECT imaging of $^{177}$Lu in the presence of $^{90}$Y, which occurs in dual-isotope radiopharmaceutical therapy (RPT) involving both isotopes. We used the GATE Monte Carlo simulation toolkit to conduct a phantom study, simulating spheres filled with $^{177}$Lu and $^{90}$Y placed in a cylindrical water phantom that was also filled with activity of both radionuclides. We simulated multiple phantom configurations and activity combinations by varying the location of the spheres, the concentrations of $^{177}$Lu and $^{90}$Y in the spheres, and the amount of background activity. We investigated two different scatter window widths to be used with triple energy window (TEW) scatter correction. We also created multiple realizations of each configuration to improve our assessment, leading to a total of 540 simulations. Each configuration was imaged using a simulated Siemens SPECT camera. The projections were reconstructed using the standard 3D OSEM algorithm, and errors associated with $^{177}$Lu activity quantification and contrast-to-noise ratios (CNRs) were determined. In all configurations, the quantification error was within $\pm$6% of the no-$^{90}$Y case, and we found that quantitative accuracy may slightly improve when $^{90}$Y is present because of reduction of errors associated with TEW scatter correction. The CNRs were not significantly impacted by the presence of $^{90}$Y, but they were increased when a wider scatter window width was used for TEW scatter correction. The width of the scatter windows made a small but statistically significant difference of 1-2% on the recovered $^{177}$Lu activity. Based on these results, we can conclude that activity quantification of $^{177}$Lu and lesion detectability is not degraded by the presence of $^{90}$Y.
|
https://arxiv.org/abs/2301.10870v1
|
2301.10870
|
2023-01-25
|
cybersecurity
|
$^{178}$Hg and asymmetric fission of neutron-deficient pre-actinides
|
Fission at low excitation energy is an ideal playground to probe the impact of nuclear structure on nuclear dynamics. While the importance of structural effects in the nascent fragments is well-established in the (trans-)actinide region, the observation of asymmetric fission in several neutron-deficient pre-actinides can be explained by various mechanisms. To deepen our insight into that puzzle, an innovative approach based on inverse kinematics and an enhanced version of the VAMOS++ heavy-ion spectrometer was implemented at the GANIL facility, Caen. Fission of $^{178}$Hg was induced by fusion of $^{124}$Xe and $^{54}$Fe. The two fragments were detected in coincidence using VAMOS++ supplemented with a new SEcond Detection arm. For the first time in the pre-actinide region, access to the pre-neutron mass and total kinetic energy distributions, and the simultaneous isotopic identification of one the fission fragment, was achieved. The present work describes the experimental approach, and discusses the pre-neutron observables in the context of an extended asymmetric-fission island located south-west of $^{208}Pb. A comparison with different models is performed, demonstrating the importance of this "new" asymmetric-fission island for elaborating on driving effects in fission.
|
https://arxiv.org/abs/2211.01879v1
|
2211.01879
|
2022-11-03
|
cybersecurity
|
$^{179}$Ta(n,$γ$) cross-section measurement and the astrophysical origin of $^{180}$Ta isotope
|
Tantalum-180m is nature's rarest (quasi) stable isotope and its astrophysical origin is an open question. A possible production site of this isotope is the slow neutron capture process in Asymptotic Giant Branch stars, where it can be produced via neutron capture reactions on unstable $^{179}$Ta. We report a new measurement of the $^{179}$Ta($n,\gamma$)$^{180}$Ta cross section at thermal neutron energies via the activation technique. Our results for the thermal and resonance-integral cross-sections are 952 $\pm$ 57 b and 2013 $\pm$ 148 b, respectively. The thermal cross section is in good agreement with the only previous measurement (Phys. Rev C {\bf 60} 025802, 1999), while the resonance integral is different by a factor of $\approx$1.7. While neutron energies in this work are smaller than the energies in a stellar environment, our results may lead to improvements in theoretical predictions of the stellar cross section.
|
https://arxiv.org/abs/2304.06799v1
|
2304.06799
|
2023-04-13
|
cybersecurity
|
17 GHz Lossless InP-Membrane Active Metasurface
|
High-speed active metasurfaces enable spatiotemporal control of incident light within an ultra-thin layer, offering new possibilities for optical communication, computing, and sensing. However, a fundamental tradeoff between electrical conductivity and optical absorption of the material has hindered the realization of active metasurfaces that simultaneously achieve broad modulation bandwidth and low optical loss. Here, we experimentally demonstrate a high-speed active metasurface operating in the 1.5-{\mu}m wavelength range that realizes a record-high modulation bandwidth of 17.5 GHz, while maintaining a high quality (Q) factor of 102 and an ultra-low optical loss of 0.56 dB. The key enabling technology is the indium-phosphide (InP) membrane platform; an n-type InP offers both high electron mobility and low free-carrier optical absorption, making it an ideal material for active metasurface devices. The high-Q Friedrich-Wintgen quasi-bound-states-in-the-continuum mode inside the InP-membrane high-contrast grating (HCG) is utilized to trap the normally incident light within an organic electro-optic (OEO) material, enabling efficient modulation. InP HCG also serves as an ultralow-resistance interdigitated electrodes for applying high-speed electrical signals to the OEO material, thereby offering 50-fold improvement in modulation bandwidth compared to conventional silicon-based counterparts. Our work paves the way towards high-speed, low-loss active metasurfaces for spatiotemporal control of light beyond the gigahertz regime.
|
https://arxiv.org/abs/2505.07072v1
|
2505.07072
|
2025-05-11
|
cybersecurity
|
17O enrichment of CaWO4 crystals for spin-dependent DM search
|
For many years, various experiments have attempted to shed light on the nature of dark matter (DM). This work investigates the possibility of using CaWO4 crystals for the direct search of spin-dependent DM interactions using the isotope 17O with a nuclear spin of 5/2. Due to the low natural abundance of 0.038%, an enrichment of the CaWO4 crystals with 17O is developed during the crystal production process at the Technical University of Munich. Three CaWO4 crystals were enriched, and their 17O content was measured by nuclear magnetic resonance spectroscopy at the University of Leipzig. This paper presents the concept and first results of the 17O enrichment and discusses the possibility of using enriched crystals to increase the sensitivity for the spin-dependent DM search with CRESST.
|
https://arxiv.org/abs/2311.03161v1
|
2311.03161
|
2023-11-06
|
cybersecurity
|
17T7 is a Galois group over the rationals
|
We prove that the transitive permutation group 17T7, isomorphic to a split extension of $C_2$ by $\mathrm{PSL}_2(\mathbb{F}_{16})$, is a Galois group over the rationals. The group arises from the field of definition of the 2-torsion on an abelian fourfold with real multiplication defined over a real quadratic field. We find such fourfolds using Hilbert modular forms. Finally, building upon work of Demb\'el\'e, we show how to conjecturally reconstruct a period matrix for an abelian variety attached to a Hilbert modular form; we then use this to exhibit an explicit degree 17 polynomial with Galois group 17T7.
|
https://arxiv.org/abs/2411.07857v2
|
2411.07857
|
2024-11-12
|
cybersecurity
|
1-800-SHARED-TASKS at RegNLP: Lexical Reranking of Semantic Retrieval (LeSeR) for Regulatory Question Answering
|
This paper presents the system description of our entry for the COLING 2025 RegNLP RIRAG (Regulatory Information Retrieval and Answer Generation) challenge, focusing on leveraging advanced information retrieval and answer generation techniques in regulatory domains. We experimented with a combination of embedding models, including Stella, BGE, CDE, and Mpnet, and leveraged fine-tuning and reranking for retrieving relevant documents in top ranks. We utilized a novel approach, LeSeR, which achieved competitive results with a recall@10 of 0.8201 and map@10 of 0.6655 for retrievals. This work highlights the transformative potential of natural language processing techniques in regulatory applications, offering insights into their capabilities for implementing a retrieval augmented generation system while identifying areas for future improvement in robustness and domain adaptation.
|
https://arxiv.org/abs/2412.06009v1
|
2412.06009
|
2024-12-08
|
cybersecurity
|
1-800-SHARED-TASKS @ NLU of Devanagari Script Languages: Detection of Language, Hate Speech, and Targets using LLMs
|
This paper presents a detailed system description of our entry for the CHiPSAL 2025 shared task, focusing on language detection, hate speech identification, and target detection in Devanagari script languages. We experimented with a combination of large language models and their ensembles, including MuRIL, IndicBERT, and Gemma-2, and leveraged unique techniques like focal loss to address challenges in the natural understanding of Devanagari languages, such as multilingual processing and class imbalance. Our approach achieved competitive results across all tasks: F1 of 0.9980, 0.7652, and 0.6804 for Sub-tasks A, B, and C respectively. This work provides insights into the effectiveness of transformer models in tasks with domain-specific and linguistic challenges, as well as areas for potential improvement in future iterations.
|
https://arxiv.org/abs/2411.06850v1
|
2411.06850
|
2024-11-11
|
cybersecurity
|
180$^\circ$ Rotations in the Polarization Angle for Blazars
|
Rotations of the electric vector position angle (EVPA) in blazars are often
close to an integral multiple of 180$^\circ$. There are multiple examples of
this in the literature, and our analysis here, of the optical polarization data
from the RoboPol monitoring program, strengthens the evidence by showing that
$n\pi$ rotations occur more frequently than expected by chance. We explain this
with a model consisting of two polarized emission components: a "jet" that is
constant in time, and a "burst" that is variable. The EVPA of the combination
is $\rm EVPA_{jet}$ at both the beginning and the end of the burst, so the net
rotation across the burst must be $n\pi$. Examples are analyzed on the Stokes
plane, where the winding number for the Stokes vector of the combination gives
the value of $n$. The main conclusion is that the EVPA rotation can be much
larger than the physical rotation of the emission region around the axis of the
jet, but this requires the EVPAs of the jet and the burst to be nearly
orthogonal. A shock-in-jet calculation by Zhang et al. can provide a physical
model for our toy model, and in addition automatically gives the needed
orthogonality. The model is illustrated with data on OJ287 published by
Myserlis et al., and we suggest that the large rapid EVPA rotation seen there
might be a phase effect and not representative of a physical rotation.
|
http://arxiv.org/abs/2003.07090v1
|
2003.07090
|
2020-03-16
|
cybersecurity
|
180$^\circ$-twisted bilayer ReSe$_2$ as an artificial noncentrosymmetric semiconductor
|
We have fabricated a 180$^\circ$-twisted bilayer ReSe$_2$ by stacking two centrosymmetric monolayer ReSe$_2$ flakes in opposite directions, which is expected to lose spatial inversion symmetry. By the second harmonic generation and angle-resolved photoemission spectroscopy, we successfully observed spatial inversion symmetry breaking and emergent band dispersions. The band calculation shows the finite lifting of spin degeneracy (~50 meV) distinct from natural monolayer and bilayer ReSe$_2$. Our results demonstrate that the spin-momentum locked state, which leads to spintronic functions and Berry-curvature-related phenomena, can be realized even with the stacking of centrosymmetric monolayers.
|
https://arxiv.org/abs/2309.15403v1
|
2309.15403
|
2023-09-27
|
cybersecurity
|
180 Days After EIP-4844: Will Blob Sharing Solve Dilemma for Small Rollups?
|
The introduction of blobs through EIP-4844 has significantly reduced the Data Availability (DA) costs for rollups on Ethereum. However, due to the fixed size of blobs at 128 KB, rollups with low data throughput face a dilemma: they either use blobs inefficiently or decrease the frequency of DA submissions. Blob sharing, where multiple rollups share a single blob, has been proposed as a solution to this problem. This paper examines the effectiveness of blob sharing based on real-world data collected approximately six months after the implementation of EIP-4844. By simulating cost changes using a simple blob sharing format, we demonstrate that blob sharing can substantially improve the costs and DA service quality for small rollups, effectively resolving their dilemma. Notably, we observed cost reductions in USD exceeding 85% for most of the rollups when they cooperate, attributable to the smoothing effect of the blob base fee achieved through blob sharing.
|
https://arxiv.org/abs/2410.04111v2
|
2410.04111
|
2024-10-05
|
cybersecurity
|
180 degree Ferroelectric Stripe Nanodomains in BiFeO3 Thin Films
|
There is growing evidence that domain walls in ferroics can possess emergent
properties that are absent in bulk materials. For example, 180 domain walls in
the ferroelectric-antiferromagnetic BiFeO3 are particularly interesting because
they have been predicted to possess a range of intriguing behaviors; including
electronic conduction and enhanced magnetization. To date, however, ordered
arrays of such domain structures have not been reported. Here, we report the
observation of 180 stripe nanodomains in (110)-oriented BiFeO3 thin films grown
on orthorhombic GdScO3 (010)O substrates, and their impact on exchange coupling
to metallic ferromagnets. Nanoscale ferroelectric 180 stripe domains with {112
} domain walls were observed in films < 32 nm thick to compensate for large
depolarization fields. With increasing film thickness, we observe a domain
structure crossover from the depolarization field-driven 180 stripe nanodomains
to 71 domains determined by the elastic energy. Interestingly, these 180 domain
walls (which are typically cylindrical or meandering in nature due to a lack of
strong anisotropy associated with the energy of such walls) are found to be
highly-ordered. Additional studies of Co0.9Fe0.1/BiFeO3 heterostructures reveal
exchange bias and exchange enhancement in heterostructures based-on BiFeO3 with
180 domain walls and an absence of exchange bias in heterostructures based-on
BiFeO3 with 71 domain walls; suggesting that the 180 domain walls could be the
possible source for pinned uncompensated spins that give rise to exchange bias.
This is further confirmed by X-ray circular magnetic dichroism studies, which
demonstrate that films with predominantly 180 domain walls have larger
magnetization than those with primarily 71 domain walls. Our results could be
useful to extract the structure of domain walls and to explore domain wall
functionalities in BiFeO3.
|
http://arxiv.org/abs/1508.07376v1
|
1508.07376
|
2015-08-28
|
cybersecurity
|
180-degree Outpainting from a Single Image
|
Presenting context images to a viewer's peripheral vision is one of the most effective techniques to enhance immersive visual experiences. However, most images only present a narrow view, since the field-of-view (FoV) of standard cameras is small. To overcome this limitation, we propose a deep learning approach that learns to predict a 180{\deg} panoramic image from a narrow-view image. Specifically, we design a foveated framework that applies different strategies on near-periphery and mid-periphery regions. Two networks are trained separately, and then are employed jointly to sequentially perform narrow-to-90{\deg} generation and 90{\deg}-to-180{\deg} generation. The generated outputs are then fused with their aligned inputs to produce expanded equirectangular images for viewing. Our experimental results show that single-view-to-panoramic image generation using deep learning is both feasible and promising.
|
https://arxiv.org/abs/2001.04568v1
|
2001.04568
|
2020-01-13
|
cybersecurity
|
180-degree phase shift of magnetoelastic waves observed by phase-resolved spin-wave tomography
|
We have investigated optically-excited magnetoelastic waves by phase-resolved
spin-wave tomography (PSWaT). PSWaT reconstructs dispersion relation of spin
waves together with their phase information by using time-resolved
magneto-optical imaging for spin-wave propagation followed by an analysis based
on the convolution theorem and a complex Fourier transform. In PSWaT spectra
for a Bi-doped garnet film, we found a 180 degree phase shift of magnetoelastic
waves at around the crossing of the dispersion relations of spin and elastic
waves. The result is explained by a coupling between spin waves and elastic
waves through magnetoelastic interaction. We also propose an efficient way for
phase manipulation of magnetoelastic waves by rotating the orientation of
magnetization less than 10 degree.
|
http://arxiv.org/abs/1803.07697v1
|
1803.07697
|
2018-03-21
|
cybersecurity
|
18-22 cm VLBA Faraday rotation studies of six AGN jets
|
The formation of relativistic jets in active galactic nuclei (AGN) is related
to accretion on to their central supermassive black holes, and magnetic fields
are believed to play a central role in launching, collimating and accelerating
the jet streams from very compact regions out to kiloparsec or megaparsec
scales. In the presence of helical or toroidal magnetic fields threading the
AGN jets and their immediate vicinity, gradients in the observed Faraday
rotation measures are expected due to the systematic change in the
line-of-sight component of the magnetic field across the jet. We have analysed
total intensity, linear polarization, fractional polarization and Faraday
rotation maps based on Very Long Baseline Array data obtained at four
wavelengths in the 18-22 cm range for six AGN (OJ 287, 3C 279, PKS 1510-089, 3C
345, BL Lac and 3C 454.3). These observations typically probe projected
distances out to tens of parsecs from the observed core, and are well suited
for Faraday rotation studies due to the relatively long wavelengths used and
the similarity of the structures measured at the different wavelengths. We have
identified statistically significant, monotonic, transverse Faraday rotation
gradients across the jets of four of these six sources, as well as a tentative
transverse Faraday rotation gradient across the jet of OJ 287, providing
evidence for the presence of toroidal magnetic fields, which may be one
component of helical magnetic fields associated with these AGN jets.
|
http://arxiv.org/abs/1702.06659v1
|
1702.06659
|
2017-02-22
|
cybersecurity
|
183 GHz water megamasers in active galactic nuclei: a new accretion disk tracer
|
We present the results of an ALMA survey to identify 183 GHz H$_2$O maser emission from AGN already known to host 22 GHz megamaser systems. Out of 20 sources observed, we detect significant 183 GHz maser emission from 13; this survey thus increases the number of AGN known to host (sub)millimeter megamasers by a factor of 5. We find that the 183 GHz emission is systematically fainter than the 22 GHz emission from the same targets, with typical flux densities being roughly an order of magnitude lower at 183 GHz than at 22 GHz. However, the isotropic luminosities of the detected 183 GHz sources are comparable to their 22 GHz values. For two of our sources -- ESO 269-G012 and the Circinus galaxy -- we detect rich 183 GHz spectral structure containing multiple line complexes. The 183 GHz spectrum of ESO 269-G012 exhibits the triple-peaked structure characteristic of an edge-on AGN disk system. The Circinus galaxy contains the strongest 183 GHz emission detected in our sample, peaking at a flux density of nearly 5 Jy. The high signal-to-noise ratios achieved by these strong lines enable a coarse mapping of the 183 GHz maser system, in which the masers appear to be distributed similarly to those seen in VLBI maps of the 22 GHz system in the same galaxy and may be tracing the circumnuclear accretion disk at larger orbital radii than are occupied by the 22 GHz masers. This newly identified population of AGN disk megamasers presents a motivation for developing VLBI capabilities at 183 GHz.
|
https://arxiv.org/abs/2302.02572v1
|
2302.02572
|
2023-02-06
|
cybersecurity
|
185 mW, 1 MHz, 15 fs carrier-envelope phase-stable pulse generation via polarization-optimized down-conversion from gas-filled hollow-core fiber
|
Gas-filled hollow core fibers allow the generation of single-cycle pulses at megahertz repetition rates. When coupled with difference frequency generation, they can be an ideal driver for the generation of carrier-envelope phase stable, octave-spanning pulses in the short-wavelength infrared. In this work, we investigate the dependence of the polarization state in gas-filled hollow-core fibers on the subsequent difference frequency generation stage. We show that by adjusting the input polarization state of light in geometrically symmetric systems, such as hollow-core fibers, one can achieve precise control over the polarization state of the output pulses. Importantly, this manipulation preserves the temporal characteristics of the ultrashort pulses generated, especially when operating near the single-cycle regime. We leverage this property to boost the down-conversion efficiency of these pulses in a type I difference frequency generation stage. Our technique overcomes the bandwidth and dispersion constraints of the previous methods that rely on broadband waveplates or adjustment of crystal axes relative to the laboratory frame. This advancement is crucial for experiments demanding pure polarization states in the eigenmodes of the laboratory frame.
|
https://arxiv.org/abs/2404.14153v1
|
2404.14153
|
2024-04-22
|
cybersecurity
|
18.8 Gbps real-time quantum random number generator with a photonic integrated chip
|
Quantum random number generators (QRNGs) can produce true random numbers. Yet, the two most important QRNG parameters highly desired for practical applications, i.e., speed and size, have to be compromised during implementations. Here, we present the fastest and miniaturized QRNG with a record real-time output rate as high as 18.8 Gbps by combining a photonic integrated chip and the technology of optimized randomness extraction. We assemble the photonic integrated circuit designed for vacuum state QRNG implementation, InGaAs homodyne detector and high-bandwidth transimpedance amplifier into a single chip using hybrid packaging, which exhibits the excellent characteristics of integration and high-frequency response. With a sample rate of 2.5 GSa/s in a 10-bit analog-to-digital converter and subsequent paralleled postprocessing in a field programmable gate array, the QRNG outputs ultrafast random bitstreams via a fiber optic transceiver, whose real-time speed is validated in a personal computer.
|
https://arxiv.org/abs/2105.13518v1
|
2105.13518
|
2021-05-28
|
cybersecurity
|
1/8-BPS Couplings and Exceptional Automorphic Functions
|
Unlike the $\mathcal{R}^4$ and $\nabla^4\mathcal{R}^4$ couplings, whose
coefficients are Langlands-Eisenstein series of the U-duality group, the
coefficient $\mathcal{E}_{(0,1)}^{(d)}$ of the $\nabla^6\mathcal{R}^4$
interaction in the low-energy effective action of type II strings compactified
on a torus $T^d$ belongs to a more general class of automorphic functions,
which satisfy Poisson rather than Laplace-type equations. In earlier work, it
was proposed that the exact coefficient is given by a two-loop integral in
exceptional field theory, with the full spectrum of mutually 1/2-BPS states
running in the loops, up to the addition of a particular Langlands-Eisenstein
series. Here we compute the weak coupling and large radius expansions of these
automorphic functions for any $d$. We find perfect agreement with perturbative
string theory up to genus three, along with non-perturbative corrections which
have the expected form for 1/8-BPS instantons and bound states of 1/2-BPS
instantons and anti-instantons. The additional Langlands-Eisenstein series
arises from a subtle cancellation between the two-loop amplitude with 1/4-BPS
states running in the loops, and the three-loop amplitude with mutually 1/2-BPS
states in the loops. For $d=4$, the result is shown to coincide with an
alternative proposal in terms of a covariantised genus-two string amplitude,
due to interesting identities between the Kawazumi-Zhang invariant of genus-two
curves and its tropical limit, and between double lattice sums for the particle
and string multiplets, which may be of independent mathematical interest.
|
http://arxiv.org/abs/2001.05562v3
|
2001.05562
|
2020-09-21
|
cybersecurity
|
$^{18}$F-FDG brain PET hypometabolism in post-SARS-CoV-2 infection: substrate for persistent/delayed disorders?
|
Purpose: Several brain complications of SARS-CoV-2 infection have been reported. It has been moreover speculated that this neurotropism could potentially cause a delayed outbreak of neuropsychiatric and neurodegenerative diseases of neuroinflammatory origin. A propagation mechanism has been proposed across the cribriform plate of the ethmoid bone, from the nose to the olfactory epithelium, and possibly afterward to other limbic structures, and deeper parts of the brain including the brainstem. Methods: Review of clinical examination, and whole-brain voxel-based analysis of $^{18}$F-FDG PET metabolism in comparison with healthy subjects (p voxel<0.001, p-cluster<0.05, uncorrected), of two patients with confirmed diagnosis of SARS-CoV-2 explored at the post-viral stage of the disease. Results: Hypometabolism of the olfactory/rectus gyrus was found on the two patients, especially one with 4-week prolonged anosmia. Additional hypometabolisms were found within amygdala, hippocampus, parahippocampus, cingulate cortex, pre-/post-central gyrus, thalamus/hypothalamus, cerebellum, pons, and medulla in the other patient who complained of delayed onset of a painful syndrome. Conclusion: These preliminary findings reinforce the hypotheses of SARS-CoV-2 neurotropism through the olfactory bulb and the possible extension of this impairment to other brain structures. $^{18}$F-FDG PET hypometabolism could constitute a cerebral quantitative biomarker of this involvement. Post-viral cohort studies are required to specify the exact relationship between such hypometabolisms and the possible persistent disorders, especially involving cognitive or emotion disturbances, residual respiratory symptoms, or painful complaints.
|
https://arxiv.org/abs/2502.09077v1
|
2502.09077
|
2025-02-13
|
cybersecurity
|
18F-FDG-PET dissemination features in diffuse large B cell lymphoma are predictive of outcome
|
We assessed the predictive value of new radiomic features characterizing the lesion dissemination in baseline 18F-FDG PET and tested whether combining them with baseline metabolic tumour volume (MTV) could improve prediction of progression free survival (PFS) and overall survival (OS) in diffuse large B cell lymphoma (DLBCL) patients.
|
https://arxiv.org/abs/2012.14179v1
|
2012.14179
|
2020-12-28
|
cybersecurity
|
$^{18}$F-PSMA-1007 salivary gland dosimetry: Comparison between different methods for dose calculation and assessment of inter- and intra-patient variability
|
Dosimetry of salivary glands (SGs) is usually implemented using simplified calculation approaches and approximated geometries. Our aims were to compare different dosimetry methods to calculate SGs absorbed doses (ADs) following 18F-PSMA-1007 injection, and to assess the AD variation across patients and single SG components. Five patients with prostate cancer recurrence underwent PET/CT acquisitions of the head and neck, 0.5, 2 and 4 hours after 18F-PSMA-1007 injection. Parotid and submandibular glands were segmented on CT to derive SGs volumes and masses, while PETs were used to derive Time-Integrated Activity Coefficients. Average ADs to single SG components or total SG (tSG) were calculated with the following methods: i) direct Monte Carlo (MC) simulation with GATE/GEANT4; ii) spherical model (SM) of OLINDA/EXM 2.1, adopting either patient-specific or standard ICRP89 organ masses (SMstd); iii) ellipsoidal model (EM); iv) MIRD approach with organ S-factors from OLINDA/EXM 2.1 and OpenDose collaboration, with or without contribution from cross irradiation originating outside the SGs. The maximum percent AD difference across SG components ({\delta}max) and across patients ({\Delta}max) were calculated. Compared to MC, ADs to single SG components were significantly underestimated by all methods (average relative differences between -14.5% and -30.4%). Using MC, SM and EM, {\delta}max were never below 25% (up to 113%). {\delta}max up to 702% were obtained with SMstd. Concerning tSG, results within 10% of the MC were obtained only if cross irradiation from the remainder of the body or from the remainder of the head was accounted for. The {\Delta}max ranged between 58% and 78% across patients. Specific masses of single SG components should always be considered given their large intra- and inter- patient variability.
|
https://arxiv.org/abs/2210.01616v1
|
2210.01616
|
2022-10-04
|
cybersecurity
|
18 GHz Solidly Mounted Resonator in Scandium Aluminum Nitride on SiO2/Ta2O5 Bragg Reflector
|
This work reports an acoustic solidly mounted resonator (SMR) at 18.64 GHz, among the highest operating frequencies reported. The device is built in scandium aluminum nitride (ScAlN) on top of silicon dioxide (SiO2) and tantalum pentoxide (Ta2O5) Bragg reflectors on silicon (Si) wafer. The stack is analyzed with X-ray reflectivity (XRR) and high-resolution X-ray diffraction (HRXRD). The resonator shows a coupling coefficient (k2) of 2.0%, high series quality factor (Qs) of 156, shunt quality factor (Qp) of 142, and maximum Bode quality factor (Qmax) of 210. The third-order harmonics at 59.64 GHz is also observed with k2 around 0.6% and Q around 40. Upon further development, the reported acoustic resonator platform can enable various front-end signal-processing functions, e.g., filters and oscillators, at future frequency range 3 (FR3) bands.
|
https://arxiv.org/abs/2407.02741v2
|
2407.02741
|
2024-07-03
|
cybersecurity
|
18 Million Links in Commit Messages: Purpose, Evolution, and Decay
|
Commit messages contain diverse and valuable types of knowledge in all aspects of software maintenance and evolution. Links are an example of such knowledge. Previous work on "9.6 million links in source code comments" showed that links are prone to decay, become outdated, and lack bidirectional traceability. We conducted a large-scale study of 18,201,165 links from commits in 23,110 GitHub repositories to investigate whether they suffer the same fate. Results show that referencing external resources is prevalent and that the most frequent domains other than github.com are the external domains of Stack Overflow and Google Code. Similarly, links serve as source code context to commit messages, with inaccessible links being frequent. Although repeatedly referencing links is rare (4%), 14% of links that are prone to evolve become unavailable over time; e.g., tutorials or articles and software homepages become unavailable over time. Furthermore, we find that 70% of the distinct links suffer from decay; the domains that occur the most frequently are related to Subversion repositories. We summarize that links in commits share the same fate as links in code, opening up avenues for future work.
|
https://arxiv.org/abs/2305.16591v1
|
2305.16591
|
2023-05-26
|
cybersecurity
|
$^{18}$O$/^{17}$O abundance ratio toward a sample of massive star forming regions with parallax distances
|
The $^{18}$O$/^{17}$O abundance ratio is, in principle, a powerful tool to estimate the relative contributions of massive stars and low- to intermediate-mass stars to the chemical enrichment of galaxies. We present $^{18}$O$/^{17}$O ratios derived from simultaneous observations of C$^{18}$O and C$^{17}$O 1-0 toward fifty-one massive star forming regions with the Institut de Radioastronomie Millim\'etrique (IRAM) 30 meter telescope. Simultaneous observations of HC$^{18}$O$^{+}$ 1-0 and HC$^{17}$O$^{+}$ 1-0 with the Yebes 40m telescope toward five sources from this sample were also done to test the consistency of $^{18}$O$/^{17}$O ratios derived from different isotopic pairs. From our improved measurements, resulting in smaller errors than previous work in the literature, we obtain a clear trend of increasing $^{18}$O$/^{17}$O ratio with increasing galactocentric distance (D$_{GC}$), which provides a significant constraint on Galactic chemical evolution (GCE) models. Current GCE models have to be improved in order to explain the observed C$^{18}$O/C$^{17}$O 1-0 gradient.
|
https://arxiv.org/abs/2304.01610v1
|
2304.01610
|
2023-04-04
|
cybersecurity
|
18-qubit entanglement with photon's three degrees of freedom
|
A central theme in quantum information science is to coherently control an
increasing number of quantum particles as well as their internal and external
degrees of freedom (DoFs), meanwhile maintaining a high level of coherence. The
ability to create and verify multiparticle entanglement with individual control
and measurement of each qubit serves as an important benchmark for quantum
technologies. To this end, genuine multipartite entanglement have been reported
up to 14 trapped ions, 10 photons, and 10 superconducting qubits. Here, we
experimentally demonstrate an 18-qubit Greenberger-Horne-Zeilinger (GHZ)
entanglement by simultaneous exploiting three different DoFs of six photons,
including their paths, polarization, and orbital angular momentum (OAM). We
develop high-stability interferometers for reversible quantum logic operations
between the photon's different DoFs with precision and efficiencies close to
unity, enabling simultaneous readout of 262,144 outcome combinations of the
18-qubit state. A state fidelity of 0.708(16) is measured, confirming the
genuine entanglement of all the 18 qubits.
|
http://arxiv.org/abs/1801.04043v1
|
1801.04043
|
2018-01-12
|
cybersecurity
|
1.8-THz-wide optical frequency comb emitted from monolithic passively mode-locked semiconductor quantum-well laser
|
We report on an optical frequency comb with 14nm (~1.8 THz) spectral
bandwidth at -3 dB level that is generated using a passively mode-locked
quantum-well (QW) laser in photonic integrated circuits (PICs) fabricated
through an InP generic photonic integration technology platform. This 21.5-GHz
colliding-pulse mode-locked laser cavity is defined by on-chip reflectors
incorporating intracavity phase modulators followed by an extra-cavity SOA as
booster amplifier. A 1.8-THz-wide optical comb spectrum is presented with
ultrafast pulse that is 0.35-ps-wide. The radio frequency beat note has a 3-dB
linewidth of 450 kHz and 35-dB SNR.
|
http://arxiv.org/abs/1709.07954v1
|
1709.07954
|
2017-09-22
|
cybersecurity
|
18-year long monitoring of the evolution of H2O vapor in the stratosphere of Jupiter with the Odin space telescope
|
Comet Shoemaker-Levy 9 impacted Jupiter in July 1994, leaving its
stratosphere with several new species, among them water vapor (H2O). With the
aid of a photochemical model H2O can be used as a dynamical tracer in the
jovian stratosphere. In this paper, we aim at constraining vertical eddy
diffusion (Kzz) at the levels where H2O resides. We monitored the H2O
disk-averaged emission at 556.936 GHz with the Odin space telescope between
2002 and 2019, covering nearly two decades. We analyzed the data with a
combination of 1D photochemical and radiative transfer models to constrain
vertical eddy diffusion in the stratosphere of Jupiter. The Odin observations
show us that the emission of H2O has an almost linear decrease of about 40%
between 2002 and 2019.We can only reproduce our time series if we increase the
magnitude of Kzz in the pressure range where H2O diffuses downward from 2002 to
2019, i.e. from ~0.2 mbar to ~5 mbar. However, this modified Kzz is
incompatible with hydrocarbon observations. We find that, even if allowance is
made for the initially large abundances of H2O and CO at the impact latitudes,
the photochemical conversion of H2O to CO2 is not sufficient to explain the
progressive decline of the H2O line emission, suggestive of additional loss
mechanisms. The Kzz we derived from the Odin observations of H2O can only be
viewed as an upper limit in the ~0.2 mbar to ~5 mbar pressure range. The
incompatibility between the interpretations made from H2O and hydrocarbon
observations probably results from 1D modeling limitations. Meridional
variability of H2O, most probably at auroral latitudes, would need to be
assessed and compared with that of hydrocarbons to quantify the role of auroral
chemistry in the temporal evolution of the H2O abundance since the SL9 impacts.
Modeling the temporal evolution of SL9 species with a 2D model would be the
next natural step.
|
http://arxiv.org/abs/2007.05415v1
|
2007.05415
|
2020-07-10
|
cybersecurity
|
1930-1937: the first $β$-rays and neutrino theories
|
The conceptual bases of Fermi's $\beta$-ray theory (at its 90th anniversary) are examined, highlighting the innovative drive and inspirational role for the progress that followed just afterwards. Moreover, the three different ideas of the neutrino born from the proposals of Pauli 1930, again Fermi 1933 and Majorana 1937 papers are discussed, emphasising the interest of the latter for current expectations.
|
https://arxiv.org/abs/2409.17824v1
|
2409.17824
|
2024-09-26
|
cybersecurity
|
1953: Fermi's "little discovery" and the birth of the numerical experiment
|
The year 1953 is pivotal for computational physics: the first application of the Monte-Carlo method is published and calculations of the so-called Fermi-Pasta-Ulam-Tsingou experiment are started. It is the beginning of the massive use in the physical sciences of numerical methods implemented on electronic computers and a decisive step in the development of modern nonlinear dynamics. This will lead to an unpredictable development during the following 70 years. We briefly review the unfolding of these events and present some recent results that show how the issues raised are still relevant today
|
https://arxiv.org/abs/2311.09769v1
|
2311.09769
|
2023-11-16
|
cybersecurity
|
1974: the discovery of the first binary pulsar
|
The 1974 discovery, by Russell A. Hulse and Joseph H. Taylor, of the first
binary pulsar PSR B1913+16, opened up new possibilities for the study of
relativistic gravity. PSR B1913+16, as well as several other binary pulsars,
provided {\it direct} observational proofs that gravity propagates at the
velocity of light and has a quadrupolar structure. Binary pulsars also provided
accurate tests of the strong-field regime of relativistic gravity. General
Relativity has passed all the binary pulsar tests with flying colors. The
discovery of binary pulsars had also very important consequences for
astrophysics: accurate measurement of neutron star masses, improved
understanding of the possible evolution scenarios for the co-evolution of
binary stars, proof of the existence of binary neutron stars emitting
gravitational waves for hundreds of millions of years, before coalescing in
catastrophic events radiating intense gravitational-wave signals, and probably
leading also to important emissions of electromagnetic radiation and neutrinos.
This article reviews the history of the discovery of the first binary pulsar,
and describes both its immediate impact, and its longer-term effect on
theoretical and experimental studies of relativistic gravity.
|
http://arxiv.org/abs/1411.3930v2
|
1411.3930
|
2015-02-17
|
cybersecurity
|
1977-2017: 40 years of decametric observations of Jupiter and the Sun with the Nancay Decameter Array
|
The Nancay Decameter Array (NDA) routinely observes low frequency (10-100
MHz) radio emissions of Jupiter and the Sun since 4 decades. The NDA
observations, acquired with a variety of receivers with increasing
performances, were the basis for numerous studies of jovian and solar radio
emissions and now form a unique long-term database spanning >3 solar cycles and
jovian revolutions. In addition, the NDA historically brought a fruitful
support to space-based radio observatories of the heliosphere, to
multi-wavelength analyses of solar activity and contributes to the development
of space weather services. After having summarized the NDA characteristics,
this article presents latest instrumental and database developments, some
recent scientific results and perspectives for the next decade.
|
http://arxiv.org/abs/1709.03821v3
|
1709.03821
|
2018-07-10
|
cybersecurity
|
$^{197}$Au($γ,\,xn;\,x\,=\,1\thicksim9$) Reaction Cross Section Measurements using Laser-Driven Ultra-Intense $γ$-Ray Source
|
We present a new method for the measurements of photonuclear reaction flux-weighted average cross sections and isomeric ratios using a laser-driven bremsstrahlung $\gamma$-ray source. An ultra-bright ultra-fast 60$\,\thicksim\,$250 MeV bremsstrahlung $\gamma$-ray source was established using the 200 TW laser facility in the Compact Laser Plasma Accelerator Laboratory, Peking University, which could cover the energy range from knocking out neutrons to producing pions. Stable quasi-monoenergetic electron beams were generated via laser wakefield acceleration with a charge of 300$\,\thicksim\,$600 pC per shot. The averaged $\gamma$-ray intensities ($\geqslant$8 MeV) were higher than 10$^{8}$ per shot and the instantaneous intensities can reach above 10$^{19}$ s$^{-1}$ with a duration time about 6.7 ps. $^{65}$Cu($\gamma,\,n$)$^{64}$Cu and $^{27}$Al($\gamma,\,x$)$^{24}$Na reactions were used as $\gamma$-ray flux monitors in the experiments. The flux-weighted average cross sections and isomeric ratios of $^{197}$Au($\gamma,\,xn;\,x\,=\,1\thicksim9$) reactions were analyzed through activation measurements. The results showed good agreement with previous works and proved this method to be accurate. The $^{197}$Au($\gamma,\,xn;\,x\,=\,7\thicksim\,9$) reaction cross sections were first achieved with the highest threshold energy of 71.410 MeV. Theoretical cross sections of TALYS 1.9 were calculated to compare with experiment results. This method offered a unique way of gaining insight into photonuclear reaction research, especially for short-lived isomers which extremely lack experimental data.
|
https://arxiv.org/abs/2209.13947v2
|
2209.13947
|
2022-09-28
|
cybersecurity
|
197 Candidates and 104 Validated Planets in K2's First Five Fields
|
We present 197 planet candidates discovered using data from the first year of
the NASA K2 mission (Campaigns 0-4), along with the results of an intensive
program of photometric analyses, stellar spectroscopy, high-resolution imaging,
and statistical validation. We distill these candidates into sets of 104
validated planets (57 in multi-planet systems), 30 false positives, and 63
remaining candidates. Our validated systems span a range of properties, with
median values of R_P = 2.3 R_E, P=8.6 d, Tef = 5300 K, and Kp=12.7 mag. Stellar
spectroscopy provides precise stellar and planetary parameters for most of
these systems. We show that K2 has increased by 30% the number of small planets
known to orbit moderately bright stars (1-4 R_E, Kp=9-13 mag). Of particular
interest are 37 planets smaller than 2 R_E, 15 orbiting stars brighter than
Kp=11.5, five receiving Earth-like irradiation levels, and several multi-planet
systems -- including four planets orbiting the M dwarf K2-72 near mean-motion
resonances. By quantifying the likelihood that each candidate is a planet we
demonstrate that our candidate sample has an overall false positive rate of
15-30%, with rates substantially lower for small candidates (< 2 R_E) and
larger for candidates with radii > 8 R_E and/or with P < 3 d. Extrapolation of
the current planetary yield suggests that K2 will discover between 500-1000
planets in its planned four-year mission -- assuming sufficient follow-up
resources are available. Efficient observing and analysis, together with an
organized and coherent follow-up strategy, is essential to maximize the
efficacy of planet-validation efforts for K2, TESS, and future large-scale
surveys.
|
http://arxiv.org/abs/1607.05263v3
|
1607.05263
|
2016-07-26
|
cybersecurity
|
1990-2020 : retours sur 30 ans d'\'echanges autour de l'identification de voix en milieu judiciaire (1990-2020: A look back at 30 years of discussions on voice identification in the judicial system)
|
Des enregistrements de voix se trouvent de plus en plus souvent au c{\oe}ur d{'}affaires judiciaires importantes, notamment de par l{'}essor de la t{\'e}l{\'e}phonie mobile. La justice demande {\`a} ce que des expertises en identification de voix soient r{\'e}alis{\'e}es alors que dans le m{\^e}me temps, la pertinence scientifique de telles expertises est fortement mise en cause par les scientifiques. Ainsi, d{\`e}s 1990, les chercheurs en communication parl{\'e}e r{\'e}unis dans le GFCP, devenu depuis AFCP, ont vot{\'e} une motion affirmant que « l{'}identification d{'}un individu par sa voix est {\`a} l{'}heure actuelle un probl{\`e}me {\`a} sa connaissance non r{\'e}solu ». Cette motion est toujours en vigueur, apr{\`e}s avoir {\'e}t{\'e} r{\'e}affirm{\'e}e en 1997 et renforc{\'e}e par une p{\'e}tition en 2002. Malgr{\'e} cela, des expertises judiciaires en identification de voix sont r{\'e}alis{\'e}es en France chaque ann{\'e}e. Cet article revient sur les actions men{\'e}es par le GFCP et l{'}AFCP depuis la motion initiale jusqu{'}aux actions contemporaines. Il se propose d{'}{\'e}valuer les r{\'e}percussions de ces actions, tant au niveau de la Justice qu{'}au niveau acad{\'e}mique.
|
https://aclanthology.org/2020.jeptalnrecital-eternal.5
| null |
2020-06-01
|
cybersecurity
|
1991T-like Supernovae
|
Understanding the nature of the luminous 1991T-like supernovae is of great importance to supernova cosmology as they are likely to have been more common in the early universe. In this paper we explore the observational properties of 1991T-like supernovae to study their relationship to other luminous, slow-declining Type~Ia supernovae (SNe Ia). From the spectroscopic and photometric criteria defined in Phillips et al. (1992), we identify 17 1991T-like supernovae from the literature. Combining these objects with ten 1991T-like supernovae from the Carnegie Supernova Project-II, the spectra, light curves, and colors of these events, along with their host galaxy properties, are examined in detail. We conclude that 1991T-like supernovae are closely related in essentially all of their UV, optical, and near-infrared properties -- as well as their host galaxy parameters -- to the slow-declining subset of Branch core-normal supernovae and to the intermediate 1999aa-like events, forming a continuum of luminous SNe Ia. The overriding difference between these three subgroups appears to be the extent to which $^{56}$Ni mixes into the ejecta, producing the pre-maximum spectra dominated by Fe III absorption, the broader UV light curves, and the higher luminosities that characterize the 1991T-like events. Nevertheless, the association of 1991T-like SNe with the rare Type Ia CSM supernovae would seem to run counter to this hypothesis, in which case 1991T-like events may form a separate subclass of SNe Ia, possibly arising from single-degenerate progenitor systems.
|
https://arxiv.org/abs/2405.15027v1
|
2405.15027
|
2024-05-23
|
cybersecurity
|
1991T-Like Type Ia Supernovae as an Extension of the Normal Population
|
Type Ia supernovae remain poorly understood despite decades of investigation. Massive computationally intensive hydrodynamic simulations have been developed and run to model an ever-growing number of proposed progenitor channels. Further complicating the matter, a large number of sub-types of Type Ia supernovae have been identified in recent decades. Due to the massive computational load required, inference of the internal structure of Type Ia supernovae ejecta directly from observations using simulations has previously been computationally intractable. However, deep-learning emulators for radiation transport simulations have alleviated such barriers. We perform abundance tomography on 40 Type Ia supernovae from optical spectra using the radiative transfer code TARDIS accelerated by the probabilistic DALEK deep-learning emulator. We apply a parametric model of potential ejecta structures to comparatively investigate abundance distributions and internal ionization fractions of intermediate-mass elements between normal and 1991T-like Type Ia supernovae. Our inference shows that 1991T-like Type Ia supernovae are under-abundant in the typical intermediate mass elements that heavily contribute to the spectral line formation seen in normal Type Ia supernovae at early times. Additionally, we find that the intermediate-mass elements present in 1991T-like Type Ia supernovae are highly ionized compared to those in the normal Type Ia population. Finally, we conclude that the transition between normal and 1991T-like Type Ia supernovae appears to be continuous observationally and that the observed differences come out of a combination of both abundance and ionization fractions in these supernovae populations.
|
https://arxiv.org/abs/2306.08137v1
|
2306.08137
|
2023-06-13
|
cybersecurity
|
19B isotope as a 17B-n-n three-body cluster close to unitary limit
|
We describe 19B in terms of a 17B-n-n three-body system, where the two-body subsystems 17B-n and n-n are unbound (virtual) states close to the unitary limit. The energy of 19B ground state is well reproduced and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be extended to describe the recently discovered resonant states in 20,21B.
|
https://arxiv.org/abs/2012.13342v1
|
2012.13342
|
2020-12-24
|
cybersecurity
|
19 dubious ways to compute the marginal likelihood of a phylogenetic tree topology
|
The marginal likelihood of a model is a key quantity for assessing the
evidence provided by the data in support of a model. The marginal likelihood is
the normalizing constant for the posterior density, obtained by integrating the
product of the likelihood and the prior with respect to model parameters. Thus,
the computational burden of computing the marginal likelihood scales with the
dimension of the parameter space. In phylogenetics, where we work with tree
topologies that are high-dimensional models, standard approaches to computing
marginal likelihoods are very slow. Here we study methods to quickly compute
the marginal likelihood of a single fixed tree topology. We benchmark the speed
and accuracy of 19 different methods to compute the marginal likelihood of
phylogenetic topologies on a suite of real datasets. These methods include
several new ones that we develop explicitly to solve this problem, as well as
existing algorithms that we apply to phylogenetic models for the first time.
Altogether, our results show that the accuracy of these methods varies widely,
and that accuracy does not necessarily correlate with computational burden. Our
newly developed methods are orders of magnitude faster than standard
approaches, and in some cases, their accuracy rivals the best established
estimators.
|
http://arxiv.org/abs/1811.11804v1
|
1811.11804
|
2018-11-28
|
cybersecurity
|
$^{19}$F NMR and defect spins in vacuum-annealed LaO$_{0.5}$F$_{0.5}$BiS$_2$
|
We report results of magnetization and $^{19}$F NMR measurements in the normal state of as-grown LaO$_{0.5}$F$_{0.5}$BiS$_2$. The magnetization is dominated by a temperature-independent diamagnetic component and a field- and temperature-dependent paramagnetic contribution $M_\mu(H,T)$ from a $\sim$1000~ppm concentration of local moments, an order of magnitude higher than can be accounted for by measured rare-earth impurity concentrations. $M_\mu(H,T)$ can be fit by the Brillouin function $B_J(x)$ or, perhaps more realistically, a two-level $\tanh(x)$ model for magnetic Bi $6p$ ions in defect crystal fields. Both fits require a phenomenological Curie-Weiss argument $x = \mu_\mathrm{eff}H/(T + T_W)$, $T_W \approx 1.7$ K. There is no evidence for magnetic order down to 2 K, and the origin of $T_W$ is not clear. $^{19}$F frequency shifts, linewidths, and spin-lattice relaxation rates are consistent with purely dipolar $^{19}$F/defect-spin interactions. The defect-spin correlation time $\tau_c(T)$ obtained from $^{19}$F spin-lattice relaxation rates obeys the Korringa relation $\tau_cT = \text{const.}$, indicating the relaxation is dominated by conduction-band fluctuations.
|
https://arxiv.org/abs/2408.06284v2
|
2408.06284
|
2024-08-12
|
cybersecurity
|
$^{19}$F$(p,γ)$$^{20}$Ne reaction rate and the puzzling calcium abundance in metal poor stars
|
The $^{19}$F$(p,\gamma)$$^{20}$Ne reaction is the only process to break out of the CNO cycle at temperature below 0.1 GK and may serve as the origin of calcium in first generation of stars after the Big Bang. In the recent measurement, the Jinping Underground Nuclear Experiment (JUNA) obtained the rate of $^{19}$F$(p,\gamma)$$^{20}$Ne reaction, significantly larger than the previously recommended values. In this work, we perform the theoretical studies of the $^{19}$F$(p,\gamma)$$^{20}$Ne reaction using the Gamow shell model in the coupled-channel representation (GSM-CC). At temperature around 0.1 GK, the predicted rate by GSM-CC is close to the rate found by JUNA. Thus, based on GSM-CC, the break-out reaction $^{19}$F$(p,\gamma)$$^{20}$Ne from the CNO-cycle might win over its competing reaction $^{19}$F$(p,\alpha)$$^{16}$O, and produce enough calcium in the metal poor stars.
|
https://arxiv.org/abs/2411.17243v1
|
2411.17243
|
2024-11-26
|
cybersecurity
|
19 Parameters Is All You Need: Tiny Neural Networks for Particle Physics
|
As particle accelerators increase their collision rates, and deep learning solutions prove their viability, there is a growing need for lightweight and fast neural network architectures for low-latency tasks such as triggering. We examine the potential of one recent Lorentz- and permutation-symmetric architecture, PELICAN, and present its instances with as few as 19 trainable parameters that outperform generic architectures with tens of thousands of parameters when compared on the binary classification task of top quark jet tagging.
|
https://arxiv.org/abs/2310.16121v3
|
2310.16121
|
2023-10-24
|
cybersecurity
|
19th century real analysis, forward and backward
|
19th century real analysis received a major impetus from Cauchy's work.
Cauchy mentions variable quantities, limits, and infinitesimals, but the
meaning he attached to these terms is not identical to their modern meaning.
Some Cauchy historians work in a conceptual scheme dominated by an assumption
of a teleological nature of the evolution of real analysis toward a preordained
outcome. Thus, Gilain and Siegmund-Schultze assume that references to limite in
Cauchy's work necessarily imply that Cauchy was working with an Archi-medean
continuum, whereas infinitesimals were merely a convenient figure of speech,
for which Cauchy had in mind a complete justification in terms of Archimedean
limits. However, there is another formalisation of Cauchy's procedures
exploiting his limite, more consistent with Cauchy's ubiquitous use of
infinitesimals, in terms of the standard part principle of modern infinitesimal
analysis.
We challenge a misconception according to which Cauchy was allegedly forced
to teach infinitesimals at the Ecole Polytechnique. We show that the debate
there concerned mainly the issue of rigor, a separate one from infinitesimals.
A critique of Cauchy's approach by his contemporary de Prony sheds light on the
meaning of rigor to Cauchy and his contemporaries. An attentive reading of
Cauchy's work challenges received views on Cauchy's role in the history of
analysis, and indicates that he was a pioneer of infinitesimal techniques as
much as a harbinger of the Epsilontik.
|
http://arxiv.org/abs/1907.07451v1
|
1907.07451
|
2019-07-17
|
cybersecurity
|
1-absorbing primary submodules
|
Let $R$ be a commutative ring with non-zero identity and $M$ be a unitary $R$-module. The goal of this paper is to extend the concept of 1-absorbing primary ideals to 1-absorbing primary submodules. A proper submodule $N$ of $M$ is said to be a 1-absorbing primary submodule if whenever non-unit elements $a,b\in R$ and $m\in M$ with $abm\in N$, then either $ab\in(N:_{R}M)$ or $m\in M-rad(N).$ Various properties and chacterizations of this class of submodules are considered. Moreover, 1-absorbing primary avoidance theorem is proved.
|
https://arxiv.org/abs/2102.12148v1
|
2102.12148
|
2021-02-24
|
cybersecurity
|
1-Adamantanamine implementation in surface engineering of biomimetic PVDF-based membranes for enhanced membrane distillation
|
Membrane distillation (MD) stands at the forefront of desalination technology, harnessing the power of phase change to separate water vapor from saline using minimal energy resources efficiently. In response to this challenge, membranes with tuned pores morphology and surface chemistry with biomimetic 3D pine-like structures with improved affinity to water (desalination) and/or hazardous VOC (VOC removal) were developed and studied systematically. By implementing VIPS-PVDF membranes and a green modifier of 1-adamantanamine for the first time, membranes with a revolutionary network architecture were generated. The modifier was introduced either physically to the polymeric matrix or chemically through covalent attachment onto the surface and inside the porous structure. As a result, membranes that defy wetting under extreme hydrostatic pressures (>11.5 bar) were produced while preserving unparalleled vapor transport efficiency. The 1-adamantanamine promotes transport and enhances the affinity to the VOC, ensuring excellent membrane performance at different applications of the MD process. Transport was enhanced more than 3.6 times and separation factor beta changed from 3.48 to 15.22 for MTBE removal and from 2.0 to 3.46 for EtOH removal when comparing pristine PVDF with membrane chemically modified with 1-adamantanamine (PVDF_Ch02). The process separation index during the MTBE removal changed from 20 kg m-2 h-1 (PVDF) to 297 kg m-2 h-1 (PVDF_Ch02). All materials were highly stable and durable during the MD applications. This innovative approach not only revolutionizes desalination but also holds immense promise for diverse applications beyond, particularly in the realm of wastewater treatment. A study of the icing process on a cold plate with new membranes provided deeper insight into the icing mechanism and the role of membrane LEP in it.
|
https://arxiv.org/abs/2503.15930v1
|
2503.15930
|
2025-03-20
|
cybersecurity
|
1- and 3-photon dynamical Casimir effects using nonstationary cyclic qutrit
|
We consider the nonstationary circuit QED setup in which a 3-level artificial
atom in the $\Delta$-configuration interacts with a single-mode cavity field of
natural frequency $\omega $. It is demonstrated that when some atomic energy
level(s) undergoes a weak harmonic modulation, photons can be generated from
vacuum via effective 1- and 3-photon transitions, while the atom remains
approximately in the ground state. These phenomena occur in the dispersive
regime when the modulation frequency is accurately tuned near $\omega $ and
$3\omega $, respectively, and the generated field states exhibit strikingly
different statistics from the squeezed vacuum state attained in standard cavity
dynamical Casimir effect.
|
http://arxiv.org/abs/1805.04887v2
|
1805.04887
|
2018-08-31
|
cybersecurity
|
1-arcsecond imaging of ELAIS-N1 field at 144MHz using the LoTSS survey with international LOFAR telescope
|
We present the first wide area (2.5 x 2.5 deg^2) LOFAR High Band Antenna image at a resolution of 1.2'' x 2'' with a median noise of approximately 80 microJy per beam. It was made from an 8-hour International LOFAR Telescope (ILT) observation of the ELAIS-N1 field at frequencies ranging from 120 to 168 MHz with the most up-to-date ILT imaging methods. This intermediate resolution falls between the highest possible resolution (0.3'') achievable by using all International LOFAR Telescope (ILT) baselines and the standard 6-arcsecond resolution in the LoTSS (LOFAR Two-meter Sky Survey) image products utilising the LOFAR Dutch baselines only. This is the first demonstration of the feasibility of imaging using the ILT at a resolution of around 1'', which provides unique information on source morphology at scales that fall below the surface brightness limits at higher resolutions. The total calibration and imaging computational time is approximately 52,000 core hours, nearly 5 times more than required to produce a 6'' resolution image. We also present a radio source catalogue containing 2263 sources detected over the 2.5 x 2.5 deg^2 image of the ELAIS-N1 field, with a peak intensity threshold of 5.5 sigma. The catalogue has been cross-matched with the LoTSS deep ELAIS-N1 field radio catalogue, and its flux density and positional accuracy have been investigated and corrected accordingly. We find that approximately 80% of sources which we expect to be detectable based on their peak brightness in the LoTSS 6'' resolution image are detected in this image, which is approximately a factor of two higher than for 0.3'' resolution imaging in the Lockman Hole, implying there is a wealth of information on these intermediate scales.
|
https://arxiv.org/abs/2309.16560v3
|
2309.16560
|
2023-09-28
|
cybersecurity
|
1A-Team / Martin-Luther-Universität Halle-Wittenberg@CLSciSumm 20
|
This document demonstrates our groups approach to the CL-SciSumm shared task 2020. There are three tasks in CL-SciSumm 2020. In Task 1a, we apply a Siamese neural network to identify the spans of text in the reference paper best reflecting a citation. In Task 1b, we use a SVM to classify the facet of a citation.
|
https://aclanthology.org/2020.sdp-1.31
| null | null |
cybersecurity
|
1-Bend RAC Drawings of 1-Planar Graphs
|
A graph is 1-planar if it has a drawing where each edge is crossed at most
once. A drawing is RAC (Right Angle Crossing) if the edges cross only at right
angles. The relationships between 1-planar graphs and RAC drawings have been
partially studied in the literature. It is known that there are both 1-planar
graphs that are not straight-line RAC drawable and graphs that have a
straight-line RAC drawing but that are not 1-planar. Also, straight-line RAC
drawings always exist for IC-planar graphs, a subclass of 1-planar graphs. One
of the main questions still open is whether every 1-planar graph has a RAC
drawing with at most one bend per edge. We positively answer this question.
|
http://arxiv.org/abs/1608.08418v1
|
1608.08418
|
2016-08-30
|
cybersecurity
|
1-bend Upward Planar Drawings of SP-digraphs
|
It is proved that every series-parallel digraph whose maximum vertex-degree
is $\Delta$ admits an upward planar drawing with at most one bend per edge such
that each edge segment has one of $\Delta$ distinct slopes. This is shown to be
worst-case optimal in terms of the number of slopes. Furthermore, our
construction gives rise to drawings with optimal angular resolution
$\frac{\pi}{\Delta}$. A variant of the proof technique is used to show that
(non-directed) reduced series-parallel graphs and flat series-parallel graphs
have a (non-upward) one-bend planar drawing with $\lceil\frac{\Delta}{2}\rceil$
distinct slopes if biconnected, and with $\lceil\frac{\Delta}{2}\rceil+1$
distinct slopes if connected.
|
http://arxiv.org/abs/1608.08425v1
|
1608.08425
|
2016-08-30
|
cybersecurity
|
1-bit Adam: Communication Efficient Large-Scale Training with Adam's Convergence Speed
|
Scalable training of large models (like BERT and GPT-3) requires careful optimization rooted in model design, architecture, and system capabilities. From a system standpoint, communication has become a major bottleneck, especially on commodity systems with standard TCP interconnects that offer limited network bandwidth. Communication compression is an important technique to reduce training time on such systems. One of the most effective methods is error-compensated compression, which offers robust convergence speed even under 1-bit compression. However, state-of-the-art error compensation techniques only work with basic optimizers like SGD and momentum SGD, which are linearly dependent on the gradients. They do not work with non-linear gradient-based optimizers like Adam, which offer state-of-the-art convergence efficiency and accuracy for models like BERT. In this paper, we propose 1-bit Adam that reduces the communication volume by up to $5\times$, offers much better scalability, and provides the same convergence speed as uncompressed Adam. Our key finding is that Adam's variance (non-linear term) becomes stable (after a warmup phase) and can be used as a fixed precondition for the rest of the training (compression phase). Experiments on up to 256 GPUs show that 1-bit Adam enables up to $3.3\times$ higher throughput for BERT-Large pre-training and up to $2.9\times$ higher throughput for SQuAD fine-tuning. In addition, we provide theoretical analysis for our proposed work.
|
https://arxiv.org/abs/2102.02888v2
|
2102.02888
|
2021-02-04
|
cybersecurity
|
1-bit AI Infra: Part 1.1, Fast and Lossless BitNet b1.58 Inference on CPUs
|
Recent advances in 1-bit Large Language Models (LLMs), such as BitNet and BitNet b1.58, present a promising approach to enhancing the efficiency of LLMs in terms of speed and energy consumption. These developments also enable local LLM deployment across a broad range of devices. In this work, we introduce bitnet.cpp, a tailored software stack designed to unlock the full potential of 1-bit LLMs. Specifically, we develop a set of kernels to support fast and lossless inference of ternary BitNet b1.58 LLMs on CPUs. Extensive experiments demonstrate that bitnet.cpp achieves significant speedups, ranging from 2.37x to 6.17x on x86 CPUs and from 1.37x to 5.07x on ARM CPUs, across various model sizes. The code is available at https://github.com/microsoft/BitNet.
|
https://arxiv.org/abs/2410.16144v2
|
2410.16144
|
2024-10-21
|
cybersecurity
|
1-Bit Compressive Sensing for Efficient Federated Learning Over the Air
|
For distributed learning among collaborative users, this paper develops and analyzes a communication-efficient scheme for federated learning (FL) over the air, which incorporates 1-bit compressive sensing (CS) into analog aggregation transmissions. To facilitate design parameter optimization, we theoretically analyze the efficacy of the proposed scheme by deriving a closed-form expression for the expected convergence rate of the FL over the air. Our theoretical results reveal the tradeoff between convergence performance and communication efficiency as a result of the aggregation errors caused by sparsification, dimension reduction, quantization, signal reconstruction and noise. Then, we formulate 1-bit CS based FL over the air as a joint optimization problem to mitigate the impact of these aggregation errors through joint optimal design of worker scheduling and power scaling policy. An enumeration-based method is proposed to solve this non-convex problem, which is optimal but becomes computationally infeasible as the number of devices increases. For scalable computing, we resort to the alternating direction method of multipliers (ADMM) technique to develop an efficient implementation that is suitable for large-scale networks. Simulation results show that our proposed 1-bit CS based FL over the air achieves comparable performance to the ideal case where conventional FL without compression and quantification is applied over error-free aggregation, at much reduced communication overhead and transmission latency.
|
https://arxiv.org/abs/2103.16055v1
|
2103.16055
|
2021-03-30
|
cybersecurity
|
1-Bit Compressive Sensing: Reformulation and RRSP-Based Sign Recovery Theory
|
Recently, the 1-bit compressive sensing (1-bit CS) has been studied in the
field of sparse signal recovery. Since the amplitude information of sparse
signals in 1-bit CS is not available, it is often the support or the sign of a
signal that can be exactly recovered with a decoding method. In this paper, we
first show that a necessary assumption (that has been overlooked in the
literature) should be made for some existing theories and discussions for 1-bit
CS. Without such an assumption, the found solution by some existing decoding
algorithms might be inconsistent with 1-bit measurements. This motivates us to
pursue a new direction to develop uniform and nonuniform recovery theories for
1-bit CS with a new decoding method which always generates a solution
consistent with 1-bit measurements. We focus on an extreme case of 1-bit CS, in
which the measurements capture only the sign of the product of a sensing matrix
and a signal. We show that the 1-bit CS model can be reformulated equivalently
as an $\ell_0$-minimization problem with linear constraints. This reformulation
naturally leads to a new linear-program-based decoding method, referred to as
the 1-bit basis pursuit, which is remarkably different from existing
formulations. It turns out that the uniqueness condition for the solution of
the 1-bit basis pursuit yields the so-called restricted range space property
(RRSP) of the transposed sensing matrix. This concept provides a basis to
develop sign recovery conditions for sparse signals through 1-bit measurements.
We prove that if the sign of a sparse signal can be exactly recovered from
1-bit measurements with 1-bit basis pursuit, then the sensing matrix must admit
a certain RRSP, and that if the sensing matrix admits a slightly enhanced RRSP,
then the sign of a $k$-sparse signal can be exactly recovered with 1-bit basis
pursuit.
|
http://arxiv.org/abs/1412.5514v2
|
1412.5514
|
2015-07-22
|
cybersecurity
|
1-Bit Compressive Sensing via Approximate Message Passing with Built-in Parameter Estimation
|
1-bit compressive sensing aims to recover sparse signals from quantized 1-bit measurements. Designing efficient approaches that could handle noisy 1-bit measurements is important in a variety of applications. In this paper we use the approximate message passing (AMP) to achieve this goal due to its high computational efficiency and state-of-the-art performance. In AMP the signal of interest is assumed to follow some prior distribution, and its posterior distribution can be computed and used to recover the signal. In practice, the parameters of the prior distributions are often unknown and need to be estimated. Previous works tried to find the parameters that maximize either the measurement likelihood via expectation maximization, which becomes increasingly difficult to solve in cases of complicated probability models. Here we propose to treat the parameters as unknown variables and compute their posteriors via AMP as well, so that the parameters and the signal can be recovered jointly. Compared to previous methods, the proposed approach leads to a simple and elegant parameter estimation scheme, allowing us to directly work with 1-bit quantization noise model. Experimental results show that the proposed approach generally perform much better than the other state-of-the-art methods in the zero-noise and moderate-noise regimes, and outperforms them in most of the cases in the high-noise regime.
|
https://arxiv.org/abs/2007.07679v2
|
2007.07679
|
2020-07-15
|
cybersecurity
|
1 Bit Electronically Reconfigurable Transmitarray Antenna with Out-of-Band Scatter Suppression
|
Stealthy electronically reconfigurable transmitarray antennas are essential components in wireless communication and radar detection systems. Therefore, this paper proposes a 1 bit electronically reconfigurable transmitarray antenna with out-of-band scatter suppression. The transmitarray consists of two layers, the absorptive frequency selective transmission (AFST) layer and reconfigurable transmitarray (RTA) layer, separated by air. Specifically, the AFST layer achieves out-of-band scattering suppression and in-band transmission performance by utilizing the first three resonant modes of a bent metallic strip with a centrally loaded resistor. Additionally, the RTA layer adopts a receiver-transmitter structure with an active receiving dipole and a passive orthogonal transmitting dipole. The 1 bit phase shift is achieved by alternating two pin diodes integrated on the active dipole to reverse its current direction. To evaluate the proposed design, a 256-element transmitarray prototype is designed, fabricated and measured. For scattering, the 10-dB radar cross section reduction is realized within 4~5.2 GHz and 10.9~11.4 GHz, respectively. For radiation, the measured gain is 19.9 dBi at 7.5 GHz, corresponding to an aperture efficiency of 12.1%. and the beam scanning covers 60{\deg} with gain loss of 5 dB in both two principal planes.
|
https://arxiv.org/abs/2306.10580v1
|
2306.10580
|
2023-06-18
|
cybersecurity
|
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